Save and Load Keras Models

In this Keras article, we will learn about How to Save and Load Your Keras Deep Learning Model. Keras is a simple and powerful Python library for deep learning.

Since deep learning models can take hours, days, and even weeks to train, it is important to know how to save and load them from a disk.

In this post, you will discover how to save your Keras models to files and load them up again to make predictions.

After reading this tutorial, you will know:

How to save model weights and model architecture in separate files
How to save model architecture in both YAML and JSON format
How to save model weights and architecture into a single file for later use

Tutorial Overview

If you are new to Keras or deep learning, see this step-by-step Keras tutorial.

Keras separates the concerns of saving your model architecture and saving your model weights.

Model weights are saved to an HDF5 format. This grid format is ideal for storing multi-dimensional arrays of numbers.

The model structure can be described and saved using two different formats: JSON and YAML.

In this post, you will look at three examples of saving and loading your model to a file:

Save Model to JSON
Save Model to YAML
Save Model to HDF5

The first two examples save the model architecture and weights separately. The model weights are saved into an HDF5 format file in all cases.

The examples will use the same simple network trained on the Pima Indians onset of diabetes binary classification dataset. This is a small dataset that contains all numerical data and is easy to work with. You can download this dataset and place it in your working directory with the filename “pima-indians-diabetes.csv” (update: download from here).

Confirm that you have TensorFlow v2.x installed (e.g., v2.9 as of June 2022).

Note: Saving models requires that you have the h5py library installed. It is usually installed as a dependency with TensorFlow. You can also install it easily as follows:

sudo pip install h5py

Save Your Neural Network Model to JSON

JSON is a simple file format for describing data hierarchically.

Keras provides the ability to describe any model using JSON format with a to_json() function. This can be saved to a file and later loaded via the model_from_json() function that will create a new model from the JSON specification.

The weights are saved directly from the model using the save_weights() function and later loaded using the symmetrical load_weights() function.

The example below trains and evaluates a simple model on the Pima Indians dataset. The model is then converted to JSON format and written to model.json in the local directory. The network weights are written to model.h5 in the local directory.

The model and weight data is loaded from the saved files, and a new model is created. It is important to compile the loaded model before it is used. This is so that predictions made using the model can use the appropriate efficient computation from the Keras backend.

The model is evaluated in the same way, printing the same evaluation score.


# MLP for Pima Indians Dataset Serialize to JSON and HDF5
from tensorflow.keras.models import Sequential, model_from_json
from tensorflow.keras.layers import Dense
import numpy
import os
# fix random seed for reproducibility
numpy.random.seed(7)
# load pima indians dataset
dataset = numpy.loadtxt("pima-indians-diabetes.csv", delimiter=",")
# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]
# create model
model = Sequential()
model.add(Dense(12, input_dim=8, activation='relu'))
model.add(Dense(8, activation='relu'))
model.add(Dense(1, activation='sigmoid'))
# Compile model
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
# Fit the model
model.fit(X, Y, epochs=150, batch_size=10, verbose=0)
# evaluate the model
scores = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))
 
# serialize model to JSON
model_json = model.to_json()
with open("model.json", "w") as json_file:
    json_file.write(model_json)
# serialize weights to HDF5
model.save_weights("model.h5")
print("Saved model to disk")
 
# later...
 
# load json and create model
json_file = open('model.json', 'r')
loaded_model_json = json_file.read()
json_file.close()
loaded_model = model_from_json(loaded_model_json)
# load weights into new model
loaded_model.load_weights("model.h5")
print("Loaded model from disk")
 
# evaluate loaded model on test data
loaded_model.compile(loss='binary_crossentropy', optimizer='rmsprop', metrics=['accuracy'])
score = loaded_model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (loaded_model.metrics_names[1], score[1]*100))

Note: Your results may vary given the stochastic nature of the algorithm or evaluation procedure, or differences in numerical precision. Consider running the example a few times and compare the average outcome.

Running this example provides the output below.


acc: 78.78%
Saved model to disk
Loaded model from disk
acc: 78.78%

The JSON format of the model looks like the following:


{  
   "class_name":"Sequential",
   "config":{  
      "name":"sequential_1",
      "layers":[  
         {  
            "class_name":"Dense",
            "config":{  
               "name":"dense_1",
               "trainable":true,
               "batch_input_shape":[  
                  null,
                  8
               ],
               "dtype":"float32",
               "units":12,
               "activation":"relu",
               "use_bias":true,
               "kernel_initializer":{  
                  "class_name":"VarianceScaling",
                  "config":{  
                     "scale":1.0,
                     "mode":"fan_avg",
                     "distribution":"uniform",
                     "seed":null
                  }
               },
               "bias_initializer":{  
                  "class_name":"Zeros",
                  "config":{  
 
                  }
               },
               "kernel_regularizer":null,
               "bias_regularizer":null,
               "activity_regularizer":null,
               "kernel_constraint":null,
               "bias_constraint":null
            }
         },
         {  
            "class_name":"Dense",
            "config":{  
               "name":"dense_2",
               "trainable":true,
               "dtype":"float32",
               "units":8,
               "activation":"relu",
               "use_bias":true,
               "kernel_initializer":{  
                  "class_name":"VarianceScaling",
                  "config":{  
                     "scale":1.0,
                     "mode":"fan_avg",
                     "distribution":"uniform",
                     "seed":null
                  }
               },
               "bias_initializer":{  
                  "class_name":"Zeros",
                  "config":{  
 
                  }
               },
               "kernel_regularizer":null,
               "bias_regularizer":null,
               "activity_regularizer":null,
               "kernel_constraint":null,
               "bias_constraint":null
            }
         },
         {  
            "class_name":"Dense",
            "config":{  
               "name":"dense_3",
               "trainable":true,
               "dtype":"float32",
               "units":1,
               "activation":"sigmoid",
               "use_bias":true,
               "kernel_initializer":{  
                  "class_name":"VarianceScaling",
                  "config":{  
                     "scale":1.0,
                     "mode":"fan_avg",
                     "distribution":"uniform",
                     "seed":null
                  }
               },
               "bias_initializer":{  
                  "class_name":"Zeros",
                  "config":{  
 
                  }
               },
               "kernel_regularizer":null,
               "bias_regularizer":null,
               "activity_regularizer":null,
               "kernel_constraint":null,
               "bias_constraint":null
            }
         }
      ]
   },
   "keras_version":"2.2.5",
   "backend":"tensorflow"
}

Save Your Neural Network Model to YAML

Note: This method only applies to TensorFlow 2.5 or earlier. If you run it in later versions of TensorFlow, you will see a RuntimeError with the message “Method model.to_yaml() has been removed due to security risk of arbitrary code execution. Please use model.to_json() instead.”

This example is much the same as the above JSON example, except the YAML format is used for the model specification.

Note, this example assumes that you have PyYAML 5 installed:

sudo pip install PyYAML

In this example, the model is described using YAML, saved to file model.yaml, and later loaded into a new model via the model_from_yaml() function.

Weights are handled the same way as above in the HDF5 format as model.h5.


# MLP for Pima Indians Dataset serialize to YAML and HDF5
from tensorflow.keras.models import Sequential, model_from_yaml
from tensorflow.keras.layers import Dense
import numpy
import os
# fix random seed for reproducibility
seed = 7
numpy.random.seed(seed)
# load pima indians dataset
dataset = numpy.loadtxt("pima-indians-diabetes.csv", delimiter=",")
# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]
# create model
model = Sequential()
model.add(Dense(12, input_dim=8, activation='relu'))
model.add(Dense(8, activation='relu'))
model.add(Dense(1, activation='sigmoid'))
# Compile model
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
# Fit the model
model.fit(X, Y, epochs=150, batch_size=10, verbose=0)
# evaluate the model
scores = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))
 
# serialize model to YAML
model_yaml = model.to_yaml()
with open("model.yaml", "w") as yaml_file:
    yaml_file.write(model_yaml)
# serialize weights to HDF5
model.save_weights("model.h5")
print("Saved model to disk")
 
# later...
 
# load YAML and create model
yaml_file = open('model.yaml', 'r')
loaded_model_yaml = yaml_file.read()
yaml_file.close()
loaded_model = model_from_yaml(loaded_model_yaml)
# load weights into new model
loaded_model.load_weights("model.h5")
print("Loaded model from disk")
 
# evaluate loaded model on test data
loaded_model.compile(loss='binary_crossentropy', optimizer='rmsprop', metrics=['accuracy'])
score = loaded_model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (loaded_model.metrics_names[1], score[1]*100))

Running the example displays the following output.


acc: 78.78%
Saved model to disk
Loaded model from disk
acc: 78.78%

The model described in YAML format looks like the following:


backend: tensorflow
class_name: Sequential
config:
  layers:
  - class_name: Dense
    config:
      activation: relu
      activity_regularizer: null
      batch_input_shape: !!python/tuple
      - null
      - 8
      bias_constraint: null
      bias_initializer:
        class_name: Zeros
        config: {}
      bias_regularizer: null
      dtype: float32
      kernel_constraint: null
      kernel_initializer:
        class_name: VarianceScaling
        config:
          distribution: uniform
          mode: fan_avg
          scale: 1.0
          seed: null
      kernel_regularizer: null
      name: dense_1
      trainable: true
      units: 12
      use_bias: true
  - class_name: Dense
    config:
      activation: relu
      activity_regularizer: null
      bias_constraint: null
      bias_initializer:
        class_name: Zeros
        config: {}
      bias_regularizer: null
      dtype: float32
      kernel_constraint: null
      kernel_initializer:
        class_name: VarianceScaling
        config:
          distribution: uniform
          mode: fan_avg
          scale: 1.0
          seed: null
      kernel_regularizer: null
      name: dense_2
      trainable: true
      units: 8
      use_bias: true
  - class_name: Dense
    config:
      activation: sigmoid
      activity_regularizer: null
      bias_constraint: null
      bias_initializer:
        class_name: Zeros
        config: {}
      bias_regularizer: null
      dtype: float32
      kernel_constraint: null
      kernel_initializer:
        class_name: VarianceScaling
        config:
          distribution: uniform
          mode: fan_avg
          scale: 1.0
          seed: null
      kernel_regularizer: null
      name: dense_3
      trainable: true
      units: 1
      use_bias: true
  name: sequential_1
keras_version: 2.2.5

Save Model Weights and Architecture Together

Keras also supports a simpler interface to save both the model weights and model architecture together into a single H5 file.

Saving the model in this way includes everything you need to know about the model, including:

Model weights
Model architecture
Model compilation details (loss and metrics)
Model optimizer state

This means that you can load and use the model directly without having to re-compile it as you had to in the examples above.

Note: This is the preferred way for saving and loading your Keras model.

How to Save a Keras Model

You can save your model by calling the save() function on the model and specifying the filename.

The example below demonstrates this by first fitting a model, evaluating it, and saving it to the file model.h5.


# MLP for Pima Indians Dataset saved to single file
from numpy import loadtxt
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense
# load pima indians dataset
dataset = loadtxt("pima-indians-diabetes.csv", delimiter=",")
# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]
# define model
model = Sequential()
model.add(Dense(12, input_dim=8, activation='relu'))
model.add(Dense(8, activation='relu'))
model.add(Dense(1, activation='sigmoid'))
# compile model
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
# Fit the model
model.fit(X, Y, epochs=150, batch_size=10, verbose=0)
# evaluate the model
scores = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))
# save model and architecture to single file
model.save("model.h5")
print("Saved model to disk")

Running the example fits the model, summarizes the model’s performance on the training dataset, and saves the model to file.

acc: 77.73%
Saved model to disk

You can later load this model from the file and use it.

Note that in the Keras library, there is another function doing the same, as follows:


...
# equivalent to: model.save("model.h5")
from tensorflow.keras.models import save_model
save_model(model, "model.h5")

How to Load a Keras Model

Your saved model can then be loaded later by calling the load_model() function and passing the filename. The function returns the model with the same architecture and weights.

In this case, you load the model, summarize the architecture, and evaluate it on the same dataset to confirm the weights and architecture are the same.


# load and evaluate a saved model
from numpy import loadtxt
from tensorflow.keras.models import load_model
 
# load model
model = load_model('model.h5')
# summarize model.
model.summary()
# load dataset
dataset = loadtxt("pima-indians-diabetes.csv", delimiter=",")
# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]
# evaluate the model
score = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], score[1]*100))

Running the example first loads the model, prints a summary of the model architecture, and then evaluates the loaded model on the same dataset.

The model achieves the same accuracy score, which in this case is 77%.


_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
dense_1 (Dense)              (None, 12)                108       
_________________________________________________________________
dense_2 (Dense)              (None, 8)                 104       
_________________________________________________________________
dense_3 (Dense)              (None, 1)                 9         
=================================================================
Total params: 221
Trainable params: 221
Non-trainable params: 0
_________________________________________________________________
 
acc: 77.73%

Protocol Buffer Format

While saving and loading a Keras model using HDF5 format is the recommended way, TensorFlow supports yet another format, the protocol buffer. It is considered faster to save and load a protocol buffer format, but doing so will produce multiple files. The syntax is the same, except that you do not need to provide the .h5 extension to the filename:


# save model and architecture to single file
model.save("model")
 
# ... later
 
# load model
model = load_model('model')
# print summary
model.summary()

These will create a directory “model” with the following files:


model/
|-- assets/
|-- keras_metadata.pb
|-- saved_model.pb
`-- variables/
    |-- variables.data-00000-of-00001
    `-- variables.index

This is also the format used to save a model in TensorFlow v1.x. You may encounter this when you download a pre-trained model from TensorFlow Hub.

Original article sourced at: https://machinelearningmastery.com

#keras

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Dotnet Script: Run C# Scripts From The .NET CLI

dotnet script

Run C# scripts from the .NET CLI, define NuGet packages inline and edit/debug them in VS Code - all of that with full language services support from OmniSharp.

NuGet Packages

Name	Version	Framework(s)
`dotnet-script` (global tool)		`net6.0`, `net5.0`, `netcoreapp3.1`
`Dotnet.Script` (CLI as Nuget)		`net6.0`, `net5.0`, `netcoreapp3.1`
`Dotnet.Script.Core`		`netcoreapp3.1` , `netstandard2.0`
`Dotnet.Script.DependencyModel`		`netstandard2.0`
`Dotnet.Script.DependencyModel.Nuget`		`netstandard2.0`

Installing

Prerequisites

The only thing we need to install is .NET Core 3.1 or .NET 5.0 SDK.

.NET Core Global Tool

.NET Core 2.1 introduced the concept of global tools meaning that you can install dotnet-script using nothing but the .NET CLI.

dotnet tool install -g dotnet-script

You can invoke the tool using the following command: dotnet-script
Tool 'dotnet-script' (version '0.22.0') was successfully installed.

The advantage of this approach is that you can use the same command for installation across all platforms. .NET Core SDK also supports viewing a list of installed tools and their uninstallation.

dotnet tool list -g

Package Id         Version      Commands
---------------------------------------------
dotnet-script      0.22.0       dotnet-script

dotnet tool uninstall dotnet-script -g

Tool 'dotnet-script' (version '0.22.0') was successfully uninstalled.

Windows

choco install dotnet.script

We also provide a PowerShell script for installation.

(new-object Net.WebClient).DownloadString("https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.ps1") | iex

Linux and Mac

curl -s https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.sh | bash

If permission is denied we can try with sudo

curl -s https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.sh | sudo bash

Docker

A Dockerfile for running dotnet-script in a Linux container is available. Build:

cd build
docker build -t dotnet-script -f Dockerfile ..

And run:

docker run -it dotnet-script --version

Github

You can manually download all the releases in zip format from the GitHub releases page.

Usage

Our typical helloworld.csx might look like this:

Console.WriteLine("Hello world!");

That is all it takes and we can execute the script. Args are accessible via the global Args array.

dotnet script helloworld.csx

Scaffolding

Simply create a folder somewhere on your system and issue the following command.

dotnet script init

This will create main.csx along with the launch configuration needed to debug the script in VS Code.

.
├── .vscode
│   └── launch.json
├── main.csx
└── omnisharp.json

We can also initialize a folder using a custom filename.

dotnet script init custom.csx

Instead of main.csx which is the default, we now have a file named custom.csx.

.
├── .vscode
│   └── launch.json
├── custom.csx
└── omnisharp.json

Note: Executing dotnet script init inside a folder that already contains one or more script files will not create the main.csx file.

Running scripts

Scripts can be executed directly from the shell as if they were executables.

foo.csx arg1 arg2 arg3

OSX/Linux
Just like all scripts, on OSX/Linux you need to have a #! and mark the file as executable via chmod +x foo.csx. If you use dotnet script init to create your csx it will automatically have the #! directive and be marked as executable.

The OSX/Linux shebang directive should be #!/usr/bin/env dotnet-script

#!/usr/bin/env dotnet-script
Console.WriteLine("Hello world");

You can execute your script using dotnet script or dotnet-script, which allows you to pass arguments to control your script execution more.

foo.csx arg1 arg2 arg3
dotnet script foo.csx -- arg1 arg2 arg3
dotnet-script foo.csx -- arg1 arg2 arg3

Passing arguments to scripts

All arguments after -- are passed to the script in the following way:

dotnet script foo.csx -- arg1 arg2 arg3

Then you can access the arguments in the script context using the global Args collection:

foreach (var arg in Args)
{
    Console.WriteLine(arg);
}

All arguments before -- are processed by dotnet script. For example, the following command-line

dotnet script -d foo.csx -- -d

will pass the -d before -- to dotnet script and enable the debug mode whereas the -d after -- is passed to script for its own interpretation of the argument.

NuGet Packages

dotnet script has built-in support for referencing NuGet packages directly from within the script.

#r "nuget: AutoMapper, 6.1.0"

package

Note: Omnisharp needs to be restarted after adding a new package reference

Package Sources

We can define package sources using a NuGet.Config file in the script root folder. In addition to being used during execution of the script, it will also be used by OmniSharp that provides language services for packages resolved from these package sources.

As an alternative to maintaining a local NuGet.Config file we can define these package sources globally either at the user level or at the computer level as described in Configuring NuGet Behaviour

It is also possible to specify packages sources when executing the script.

dotnet script foo.csx -s https://SomePackageSource

Multiple packages sources can be specified like this:

dotnet script foo.csx -s https://SomePackageSource -s https://AnotherPackageSource

Creating DLLs or Exes from a CSX file

Dotnet-Script can create a standalone executable or DLL for your script.

Switch	Long switch	description
-o	--output	Directory where the published executable should be placed. Defaults to a 'publish' folder in the current directory.
-n	--name	The name for the generated DLL (executable not supported at this time). Defaults to the name of the script.
	--dll	Publish to a .dll instead of an executable.
-c	--configuration	Configuration to use for publishing the script [Release/Debug]. Default is "Debug"
-d	--debug	Enables debug output.
-r	--runtime	The runtime used when publishing the self contained executable. Defaults to your current runtime.

The executable you can run directly independent of dotnet install, while the DLL can be run using the dotnet CLI like this:

dotnet script exec {path_to_dll} -- arg1 arg2

Caching

We provide two types of caching, the dependency cache and the execution cache which is explained in detail below. In order for any of these caches to be enabled, it is required that all NuGet package references are specified using an exact version number. The reason for this constraint is that we need to make sure that we don't execute a script with a stale dependency graph.

Dependency Cache

In order to resolve the dependencies for a script, a dotnet restore is executed under the hood to produce a project.assets.json file from which we can figure out all the dependencies we need to add to the compilation. This is an out-of-process operation and represents a significant overhead to the script execution. So this cache works by looking at all the dependencies specified in the script(s) either in the form of NuGet package references or assembly file references. If these dependencies matches the dependencies from the last script execution, we skip the restore and read the dependencies from the already generated project.assets.json file. If any of the dependencies has changed, we must restore again to obtain the new dependency graph.

Execution cache

In order to execute a script it needs to be compiled first and since that is a CPU and time consuming operation, we make sure that we only compile when the source code has changed. This works by creating a SHA256 hash from all the script files involved in the execution. This hash is written to a temporary location along with the DLL that represents the result of the script compilation. When a script is executed the hash is computed and compared with the hash from the previous compilation. If they match there is no need to recompile and we run from the already compiled DLL. If the hashes don't match, the cache is invalidated and we recompile.

You can override this automatic caching by passing --no-cache flag, which will bypass both caches and cause dependency resolution and script compilation to happen every time we execute the script.

Cache Location

The temporary location used for caches is a sub-directory named dotnet-script under (in order of priority):

The path specified for the value of the environment variable named DOTNET_SCRIPT_CACHE_LOCATION, if defined and value is not empty.
Linux distributions only: $XDG_CACHE_HOME if defined otherwise $HOME/.cache
macOS only: ~/Library/Caches
The value returned by Path.GetTempPath for the platform.

Debugging

The days of debugging scripts using Console.WriteLine are over. One major feature of dotnet script is the ability to debug scripts directly in VS Code. Just set a breakpoint anywhere in your script file(s) and hit F5(start debugging)

debug

Script Packages

Script packages are a way of organizing reusable scripts into NuGet packages that can be consumed by other scripts. This means that we now can leverage scripting infrastructure without the need for any kind of bootstrapping.

Creating a script package

A script package is just a regular NuGet package that contains script files inside the content or contentFiles folder.

The following example shows how the scripts are laid out inside the NuGet package according to the standard convention .

└── contentFiles
    └── csx
        └── netstandard2.0
            └── main.csx

This example contains just the main.csx file in the root folder, but packages may have multiple script files either in the root folder or in subfolders below the root folder.

When loading a script package we will look for an entry point script to be loaded. This entry point script is identified by one of the following.

A script called main.csx in the root folder
A single script file in the root folder

If the entry point script cannot be determined, we will simply load all the scripts files in the package.

The advantage with using an entry point script is that we can control loading other scripts from the package.

Consuming a script package

To consume a script package all we need to do specify the NuGet package in the #loaddirective.

The following example loads the simple-targets package that contains script files to be included in our script.

#load "nuget:simple-targets-csx, 6.0.0"

using static SimpleTargets;
var targets = new TargetDictionary();

targets.Add("default", () => Console.WriteLine("Hello, world!"));

Run(Args, targets);

Note: Debugging also works for script packages so that we can easily step into the scripts that are brought in using the #load directive.

Remote Scripts

Scripts don't actually have to exist locally on the machine. We can also execute scripts that are made available on an http(s) endpoint.

This means that we can create a Gist on Github and execute it just by providing the URL to the Gist.

This Gist contains a script that prints out "Hello World"

We can execute the script like this

dotnet script https://gist.githubusercontent.com/seesharper/5d6859509ea8364a1fdf66bbf5b7923d/raw/0a32bac2c3ea807f9379a38e251d93e39c8131cb/HelloWorld.csx

That is a pretty long URL, so why don't make it a TinyURL like this:

dotnet script https://tinyurl.com/y8cda9zt

Script Location

A pretty common scenario is that we have logic that is relative to the script path. We don't want to require the user to be in a certain directory for these paths to resolve correctly so here is how to provide the script path and the script folder regardless of the current working directory.

public static string GetScriptPath([CallerFilePath] string path = null) => path;
public static string GetScriptFolder([CallerFilePath] string path = null) => Path.GetDirectoryName(path);

Tip: Put these methods as top level methods in a separate script file and #load that file wherever access to the script path and/or folder is needed.

REPL

This release contains a C# REPL (Read-Evaluate-Print-Loop). The REPL mode ("interactive mode") is started by executing dotnet-script without any arguments.

The interactive mode allows you to supply individual C# code blocks and have them executed as soon as you press Enter. The REPL is configured with the same default set of assembly references and using statements as regular CSX script execution.

Basic usage

Once dotnet-script starts you will see a prompt for input. You can start typing C# code there.

~$ dotnet script
> var x = 1;
> x+x
2

If you submit an unterminated expression into the REPL (no ; at the end), it will be evaluated and the result will be serialized using a formatter and printed in the output. This is a bit more interesting than just calling ToString() on the object, because it attempts to capture the actual structure of the object. For example:

~$ dotnet script
> var x = new List<string>();
> x.Add("foo");
> x
List<string>(1) { "foo" }
> x.Add("bar");
> x
List<string>(2) { "foo", "bar" }
>

Inline Nuget packages

REPL also supports inline Nuget packages - meaning the Nuget packages can be installed into the REPL from within the REPL. This is done via our #r and #load from Nuget support and uses identical syntax.

~$ dotnet script
> #r "nuget: Automapper, 6.1.1"
> using AutoMapper;
> typeof(MapperConfiguration)
[AutoMapper.MapperConfiguration]
> #load "nuget: simple-targets-csx, 6.0.0";
> using static SimpleTargets;
> typeof(TargetDictionary)
[Submission#0+SimpleTargets+TargetDictionary]

Multiline mode

Using Roslyn syntax parsing, we also support multiline REPL mode. This means that if you have an uncompleted code block and press Enter, we will automatically enter the multiline mode. The mode is indicated by the * character. This is particularly useful for declaring classes and other more complex constructs.

~$ dotnet script
> class Foo {
* public string Bar {get; set;}
* }
> var foo = new Foo();

REPL commands

Aside from the regular C# script code, you can invoke the following commands (directives) from within the REPL:

Command	Description
`#load`	Load a script into the REPL (same as `#load` usage in CSX)
`#r`	Load an assembly into the REPL (same as `#r` usage in CSX)
`#reset`	Reset the REPL back to initial state (without restarting it)
`#cls`	Clear the console screen without resetting the REPL state
`#exit`	Exits the REPL

Seeding REPL with a script

You can execute a CSX script and, at the end of it, drop yourself into the context of the REPL. This way, the REPL becomes "seeded" with your code - all the classes, methods or variables are available in the REPL context. This is achieved by running a script with an -i flag.

For example, given the following CSX script:

var msg = "Hello World";
Console.WriteLine(msg);

When you run this with the -i flag, Hello World is printed, REPL starts and msg variable is available in the REPL context.

~$ dotnet script foo.csx -i
Hello World
>

You can also seed the REPL from inside the REPL - at any point - by invoking a #load directive pointed at a specific file. For example:

~$ dotnet script
> #load "foo.csx"
Hello World
>

Piping

The following example shows how we can pipe data in and out of a script.

The UpperCase.csx script simply converts the standard input to upper case and writes it back out to standard output.

using (var streamReader = new StreamReader(Console.OpenStandardInput()))
{
    Write(streamReader.ReadToEnd().ToUpper());
}

We can now simply pipe the output from one command into our script like this.

echo "This is some text" | dotnet script UpperCase.csx
THIS IS SOME TEXT

Debugging

The first thing we need to do add the following to the launch.config file that allows VS Code to debug a running process.

{
    "name": ".NET Core Attach",
    "type": "coreclr",
    "request": "attach",
    "processId": "${command:pickProcess}"
}

To debug this script we need a way to attach the debugger in VS Code and the simplest thing we can do here is to wait for the debugger to attach by adding this method somewhere.

public static void WaitForDebugger()
{
    Console.WriteLine("Attach Debugger (VS Code)");
    while(!Debugger.IsAttached)
    {
    }
}

To debug the script when executing it from the command line we can do something like

WaitForDebugger();
using (var streamReader = new StreamReader(Console.OpenStandardInput()))
{
    Write(streamReader.ReadToEnd().ToUpper()); // <- SET BREAKPOINT HERE
}

Now when we run the script from the command line we will get

$ echo "This is some text" | dotnet script UpperCase.csx
Attach Debugger (VS Code)

This now gives us a chance to attach the debugger before stepping into the script and from VS Code, select the .NET Core Attach debugger and pick the process that represents the executing script.

Once that is done we should see our breakpoint being hit.

Configuration(Debug/Release)

By default, scripts will be compiled using the debug configuration. This is to ensure that we can debug a script in VS Code as well as attaching a debugger for long running scripts.

There are however situations where we might need to execute a script that is compiled with the release configuration. For instance, running benchmarks using BenchmarkDotNet is not possible unless the script is compiled with the release configuration.

We can specify this when executing the script.

dotnet script foo.csx -c release

Nullable reference types

Starting from version 0.50.0, dotnet-script supports .Net Core 3.0 and all the C# 8 features. The way we deal with nullable references types in dotnet-script is that we turn every warning related to nullable reference types into compiler errors. This means every warning between CS8600 and CS8655 are treated as an error when compiling the script.

Nullable references types are turned off by default and the way we enable it is using the #nullable enable compiler directive. This means that existing scripts will continue to work, but we can now opt-in on this new feature.

#!/usr/bin/env dotnet-script

#nullable enable

string name = null;

Trying to execute the script will result in the following error

main.csx(5,15): error CS8625: Cannot convert null literal to non-nullable reference type.

We will also see this when working with scripts in VS Code under the problems panel.

Download Details:
Author: filipw
Source Code: https://github.com/filipw/dotnet-script
License: MIT License

#dotnet #aspdotnet #csharp

Sasha Roberts

1659500100

Reform: Form Objects Decoupled From Models In Ruby

Reform

Form objects decoupled from your models.

Reform gives you a form object with validations and nested setup of models. It is completely framework-agnostic and doesn't care about your database.

Although reform can be used in any Ruby framework, it comes with Rails support, works with simple_form and other form gems, allows nesting forms to implement has_one and has_many relationships, can compose a form from multiple objects and gives you coercion.

Full Documentation

Reform is part of the Trailblazer framework. Full documentation is available on the project site.

Reform 2.2

Temporary note: Reform 2.2 does not automatically load Rails files anymore (e.g. ActiveModel::Validations). You need the reform-rails gem, see Installation.

Defining Forms

Forms are defined in separate classes. Often, these classes partially map to a model.

class AlbumForm < Reform::Form
  property :title
  validates :title, presence: true
end

Fields are declared using ::property. Validations work exactly as you know it from Rails or other frameworks. Note that validations no longer go into the model.

The API

Forms have a ridiculously simple API with only a handful of public methods.

#initialize always requires a model that the form represents.
#validate(params) updates the form's fields with the input data (only the form, not the model) and then runs all validations. The return value is the boolean result of the validations.
#errors returns validation messages in a classic ActiveModel style.
#sync writes form data back to the model. This will only use setter methods on the model(s).
#save (optional) will call #save on the model and nested models. Note that this implies a #sync call.
#prepopulate! (optional) will run pre-population hooks to "fill out" your form before rendering.

In addition to the main API, forms expose accessors to the defined properties. This is used for rendering or manual operations.

Setup

In your controller or operation you create a form instance and pass in the models you want to work on.

class AlbumsController
  def new
    @form = AlbumForm.new(Album.new)
  end

This will also work as an editing form with an existing album.

def edit
  @form = AlbumForm.new(Album.find(1))
end

Reform will read property values from the model in setup. In our example, the AlbumForm will call album.title to populate the title field.

Rendering Forms

Your @form is now ready to be rendered, either do it yourself or use something like Rails' #form_for, simple_form or formtastic.

= form_for @form do |f|
  = f.input :title

Nested forms and collections can be easily rendered with fields_for, etc. Note that you no longer pass the model to the form builder, but the Reform instance.

Optionally, you might want to use the #prepopulate! method to pre-populate fields and prepare the form for rendering.

Validation

After form submission, you need to validate the input.

class SongsController
  def create
    @form = SongForm.new(Song.new)

    #=> params: {song: {title: "Rio", length: "366"}}

    if @form.validate(params[:song])

The #validate method first updates the values of the form - the underlying model is still treated as immutuable and remains unchanged. It then runs all validations you provided in the form.

It's the only entry point for updating the form. This is per design, as separating writing and validation doesn't make sense for a form.

This allows rendering the form after validate with the data that has been submitted. However, don't get confused, the model's values are still the old, original values and are only changed after a #save or #sync operation.

Syncing Back

After validation, you have two choices: either call #save and let Reform sort out the rest. Or call #sync, which will write all the properties back to the model. In a nested form, this works recursively, of course.

It's then up to you what to do with the updated models - they're still unsaved.

Saving Forms

The easiest way to save the data is to call #save on the form.

if @form.validate(params[:song])
  @form.save  #=> populates album with incoming data
              #   by calling @form.album.title=.
else
  # handle validation errors.
end

This will sync the data to the model and then call album.save.

Sometimes, you need to do saving manually.

Default values

Reform allows default values to be provided for properties.

class AlbumForm < Reform::Form
  property :price_in_cents, default: 9_95
end

Saving Forms Manually

Calling #save with a block will provide a nested hash of the form's properties and values. This does not call #save on the models and allows you to implement the saving yourself.

The block parameter is a nested hash of the form input.

  @form.save do |hash|
    hash      #=> {title: "Greatest Hits"}
    Album.create(hash)
  end

You can always access the form's model. This is helpful when you were using populators to set up objects when validating.

  @form.save do |hash|
    album = @form.model

    album.update_attributes(hash[:album])
  end

Nesting

Reform provides support for nested objects. Let's say the Album model keeps some associations.

class Album < ActiveRecord::Base
  has_one  :artist
  has_many :songs
end

The implementation details do not really matter here, as long as your album exposes readers and writes like Album#artist and Album#songs, this allows you to define nested forms.

class AlbumForm < Reform::Form
  property :title
  validates :title, presence: true

  property :artist do
    property :full_name
    validates :full_name, presence: true
  end

  collection :songs do
    property :name
  end
end

You can also reuse an existing form from elsewhere using :form.

property :artist, form: ArtistForm

Nested Setup

Reform will wrap defined nested objects in their own forms. This happens automatically when instantiating the form.

album.songs #=> [<Song name:"Run To The Hills">]

form = AlbumForm.new(album)
form.songs[0] #=> <SongForm model: <Song name:"Run To The Hills">>
form.songs[0].name #=> "Run To The Hills"

Nested Rendering

When rendering a nested form you can use the form's readers to access the nested forms.

= text_field :title,         @form.title
= text_field "artist[name]", @form.artist.name

Or use something like #fields_for in a Rails environment.

= form_for @form do |f|
  = f.text_field :title

  = f.fields_for :artist do |a|
    = a.text_field :name

Nested Processing

validate will assign values to the nested forms. sync and save work analogue to the non-nested form, just in a recursive way.

The block form of #save would give you the following data.

@form.save do |nested|
  nested #=> {title:  "Greatest Hits",
         #    artist: {name: "Duran Duran"},
         #    songs: [{title: "Hungry Like The Wolf"},
         #            {title: "Last Chance On The Stairways"}]
         #   }
  end

The manual saving with block is not encouraged. You should rather check the Disposable docs to find out how to implement your manual tweak with the official API.

Populating Forms

Very often, you need to give Reform some information how to create or find nested objects when validateing. This directive is called populator and documented here.

Installation

Add this line to your Gemfile:

gem "reform"

Reform works fine with Rails 3.1-5.0. However, inheritance of validations with ActiveModel::Validations is broken in Rails 3.2 and 4.0.

Since Reform 2.2, you have to add the reform-rails gem to your Gemfile to automatically load ActiveModel/Rails files.

gem "reform-rails"

Since Reform 2.0 you need to specify which validation backend you want to use (unless you're in a Rails environment where ActiveModel will be used).

To use ActiveModel (not recommended because very out-dated).

require "reform/form/active_model/validations"
Reform::Form.class_eval do
  include Reform::Form::ActiveModel::Validations
end

To use dry-validation (recommended).

require "reform/form/dry"
Reform::Form.class_eval do
  feature Reform::Form::Dry
end

Put this in an initializer or on top of your script.

Compositions

Reform allows to map multiple models to one form. The complete documentation is here, however, this is how it works.

class AlbumForm < Reform::Form
  include Composition

  property :id,    on: :album
  property :title, on: :album
  property :songs, on: :cd
  property :cd_id, on: :cd, from: :id
end

When initializing a composition, you have to pass a hash that contains the composees.

AlbumForm.new(album: album, cd: CD.find(1))

Reform comes many more optional features, like hash fields, coercion, virtual fields, and so on. Check the full documentation here.

Reform is part of the Trailblazer project. Please buy my book to support the development and learn everything about Reform - there's two chapters dedicated to Reform!

Security And Strong_parameters

By explicitly defining the form layout using ::property there is no more need for protecting from unwanted input. strong_parameter or attr_accessible become obsolete. Reform will simply ignore undefined incoming parameters.

This is not Reform 1.x!

Temporary note: This is the README and API for Reform 2. On the public API, only a few tiny things have changed. Here are the Reform 1.2 docs.

Anyway, please upgrade and report problems and do not simply assume that we will magically find out what needs to get fixed. When in trouble, join us on Gitter.

Full documentation for Reform is available online, or support us and grab the Trailblazer book. There is an Upgrading Guide to help you migrate through versions.

Attributions!!!

Great thanks to Blake Education for giving us the freedom and time to develop this project in 2013 while working on their project.

Author: trailblazer
Source code: https://github.com/trailblazer/reform
License: MIT license

#ruby #ruby-on-rails

Sedrick Carroll

1595422560

Keras Tutorial - Ultimate Guide to Deep Learning - DataFlair

Welcome to DataFlair Keras Tutorial. This tutorial will introduce you to everything you need to know to get started with Keras. You will discover the characteristics, features, and various other properties of Keras. This article also explains the different neural network layers and the pre-trained models available in Keras. You will get the idea of how Keras makes it easier to try and experiment with new architectures in neural networks. And how Keras empowers new ideas and its implementation in a faster, efficient way.

Introduction to Keras

Keras is an open-source deep learning framework developed in python. Developers favor Keras because it is user-friendly, modular, and extensible. Keras allows developers for fast experimentation with neural networks.

Keras is a high-level API and uses Tensorflow, Theano, or CNTK as its backend. It provides a very clean and easy way to create deep learning models.

Characteristics of Keras

Keras has the following characteristics:

It is simple to use and consistent. Since we describe models in python, it is easy to code, compact, and easy to debug.
Keras is based on minimal substructure, it tries to minimize the user actions for common use cases.
Keras allows us to use multiple backends, provides GPU support on CUDA, and allows us to train models on multiple GPUs.
It offers a consistent API that provides necessary feedback when an error occurs.
Using Keras, you can customize the functionalities of your code up to a great extent. Even small customization makes a big change because these functionalities are deeply integrated with the low-level backend.

Benefits of using Keras

The following major benefits of using Keras over other deep learning frameworks are:

The simple API structure of Keras is designed for both new developers and experts.
The Keras interface is very user friendly and is pretty optimized for general use cases.
In Keras, you can write custom blocks to extend it.
Keras is the second most popular deep learning framework after TensorFlow.
Tensorflow also provides Keras implementation using its tf.keras module. You can access all the functionalities of Keras in TensorFlow using tf.keras.

Keras Installation

Before installing TensorFlow, you should have one of its backends. We prefer you to install Tensorflow. Install Tensorflow and Keras using pip python package installer.

Starting with Keras

The basic data structure of Keras is model, it defines how to organize layers. A simple type of model is the Sequential model, a sequential way of adding layers. For more flexible architecture, Keras provides a Functional API. Functional API allows you to take multiple inputs and produce outputs.

Keras Sequential model

Keras Functional API

It allows you to define more complex models.

#keras tutorials #introduction to keras #keras models #keras tutorial #layers in keras #why learn keras

Christine Brush

1591861777

Keras Models - Types and Examples

A model is the basic data structure of Keras. Keras models define how to organize layers. In this article, we will discuss Keras Models and its two types with examples. We will also learn about Model subclassing through which we can create our own fully-customizable models.

Types of Keras Models

Models in keras are available in two types:

Keras Sequential Model
Keras Functional API

#keras tutorials #functional api in keras #keras models #models in keras

Aayush Singh

1607579145

Keras Tutorial For Beginners | What is Keras | Keras Sequential Model | Keras Training

In this video on Keras, you will understand what is Keras and why do we need it, how to compose different models in Keras like the Sequential model and functional model, and later on how to define the inputs, how to connect layers over, and finally hands-on demo.
Why Keras is important

Keras is an Open Source Neural Network library written in Python that runs on top of Theano or Tensorflow. It is designed to be modular, fast, and easy to use. Keras is very quick to make a network model. If you want to make a simple network model with a few lines, Keras can help you with that.

Call Our Course Advisors IND: +91-7022374614 US: 1-800-216-8930 (Toll-Free) sales@intellipaat.com
Link: https://www.youtube.com/watch?v=nS1J-2uoKto

#keras tutorial for beginners #what is keras #keras sequential model #keras training

Save and Load Keras Models

Tutorial Overview

Save Your Neural Network Model to JSON

Save Your Neural Network Model to YAML

Save Model Weights and Architecture Together

How to Save a Keras Model

How to Load a Keras Model

Protocol Buffer Format

What is GEEK

Buddha Community

Dotnet Script: Run C# Scripts From The .NET CLI

dotnet script

NuGet Packages

Installing

Prerequisites

.NET Core Global Tool

Windows

Linux and Mac

Docker

Github

Usage

Scaffolding

Running scripts

Passing arguments to scripts

NuGet Packages

Package Sources

Creating DLLs or Exes from a CSX file

Caching

Dependency Cache

Execution cache

Cache Location

Debugging

Script Packages

Creating a script package

Consuming a script package

Remote Scripts

Script Location

REPL

Basic usage

Inline Nuget packages

Multiline mode

REPL commands

Seeding REPL with a script

Piping

Debugging

Configuration(Debug/Release)

Nullable reference types

Reform: Form Objects Decoupled From Models In Ruby

Reform

Full Documentation

Reform 2.2

Defining Forms

The API

Setup

Rendering Forms

Validation

Syncing Back

Saving Forms

Default values

Saving Forms Manually

Nesting

Nested Setup

Nested Rendering

Nested Processing

Populating Forms

Installation

Compositions

More

Security And Strong_parameters

This is not Reform 1.x!

Attributions!!!

Keras Tutorial - Ultimate Guide to Deep Learning - DataFlair

Introduction to Keras

Characteristics of Keras

Benefits of using Keras

Keras Installation

Starting with Keras

Keras Sequential model

Keras Functional API

Keras Models - Types and Examples