Harsh jain

Harsh jain


What Is The Use Of Render Method In ReactJS?

While learning full stack web development, you may be wondering the Difference between render and return in reactJS

Well, to put it simply, the render method returns a single child component to be rendered by the parent, while the return method will return whatever value is passed into it to be returned up to its caller.

This may not seem like much of a difference, but it can become important when you’re working with higher-order components, stateless functional components, or memorization.

This article will explore these two methods in more detail and show you how to use them in your projects or how it works while learning full stack web development. Want to learn more about what is the use of render method in react js? Visit to blog.

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Chloe  Butler

Chloe Butler


Pdf2gerb: Perl Script Converts PDF Files to Gerber format


Perl script converts PDF files to Gerber format

Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.

The general workflow is as follows:

  1. Design the PCB using your favorite CAD or drawing software.
  2. Print the top and bottom copper and top silk screen layers to a PDF file.
  3. Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
  4. Use a Gerber viewer to double-check the output against the original PCB design.
  5. Make adjustments as needed.
  6. Submit the files to a PCB manufacturer.

Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).

See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.


#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;

use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)

#configurable settings:
#change values here instead of in main pfg2gerb.pl file

use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call

#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software.  \nGerber files MAY CONTAIN ERRORS.  Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG

use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC

use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)

#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1); 

#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
#round or square pads (> 0) and drills (< 0):
    .010, -.001,  #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
    .031, -.014,  #used for vias
    .041, -.020,  #smallest non-filled plated hole
    .051, -.025,
    .056, -.029,  #useful for IC pins
    .070, -.033,
    .075, -.040,  #heavier leads
#    .090, -.043,  #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
    .100, -.046,
    .115, -.052,
    .130, -.061,
    .140, -.067,
    .150, -.079,
    .175, -.088,
    .190, -.093,
    .200, -.100,
    .220, -.110,
    .160, -.125,  #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
    .090, -.040,  #want a .090 pad option, but use dummy hole size
    .065, -.040, #.065 x .065 rect pad
    .035, -.040, #.035 x .065 rect pad
    .001,  #too thin for real traces; use only for board outlines
    .006,  #minimum real trace width; mainly used for text
    .008,  #mainly used for mid-sized text, not traces
    .010,  #minimum recommended trace width for low-current signals
    .015,  #moderate low-voltage current
    .020,  #heavier trace for power, ground (even if a lighter one is adequate)
    .030,  #heavy-current traces; be careful with these ones!
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);

#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size:   parsed PDF diameter:      error:
#  .014                .016                +.002
#  .020                .02267              +.00267
#  .025                .026                +.001
#  .029                .03167              +.00267
#  .033                .036                +.003
#  .040                .04267              +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
    HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
    RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
    SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
    RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
    TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
    REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects

#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
    CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
    CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
    SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
    WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
    RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found

#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches

#line join/cap styles:
use constant
    CAP_NONE => 0, #butt (none); line is exact length
    CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
    CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
    CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
#number of elements in each shape type:
use constant
    RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
    LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
    CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
    CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
    rect => RECT_SHAPELEN,
    line => LINE_SHAPELEN,
    curve => CURVE_SHAPELEN,
    circle => CIRCLE_SHAPELEN,

#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions

# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?

#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes. 
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes

#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches

# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)

# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time

# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const

use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool

my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time

print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load


#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html

#my $caller = "pdf2gerb::";

#sub cfg
#    my $proto = shift;
#    my $class = ref($proto) || $proto;
#    my $settings =
#    {
#        $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
#    };
#    bless($settings, $class);
#    return $settings;

#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;

#print STDERR "read cfg file\n";

#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names

#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }

Download Details:

Author: swannman
Source Code: https://github.com/swannman/pdf2gerb

License: GPL-3.0 license


Beth  Cooper

Beth Cooper


Easy Activity Tracking for Models, Similar to Github's Public Activity


public_activity provides easy activity tracking for your ActiveRecord, Mongoid 3 and MongoMapper models in Rails 3 and 4.

Simply put: it can record what happens in your application and gives you the ability to present those recorded activities to users - in a similar way to how GitHub does it.

!! WARNING: README for unreleased version below. !!

You probably don't want to read the docs for this unreleased version 2.0.

For the stable 1.5.X readme see: https://github.com/chaps-io/public_activity/blob/1-5-stable/README.md


Here is a simple example showing what this gem is about:

Example usage



Ryan Bates made a great screencast describing how to integrate Public Activity.


A great step-by-step guide on implementing activity feeds using public_activity by Ilya Bodrov.

Online demo

You can see an actual application using this gem here: http://public-activity-example.herokuapp.com/feed

The source code of the demo is hosted here: https://github.com/pokonski/activity_blog


Gem installation

You can install public_activity as you would any other gem:

gem install public_activity

or in your Gemfile:

gem 'public_activity'

Database setup

By default public_activity uses Active Record. If you want to use Mongoid or MongoMapper as your backend, create an initializer file in your Rails application with the corresponding code inside:

For Mongoid:

# config/initializers/public_activity.rb
PublicActivity.configure do |config|
  config.orm = :mongoid

For MongoMapper:

# config/initializers/public_activity.rb
PublicActivity.configure do |config|
  config.orm = :mongo_mapper

(ActiveRecord only) Create migration for activities and migrate the database (in your Rails project):

rails g public_activity:migration
rake db:migrate

Model configuration

Include PublicActivity::Model and add tracked to the model you want to keep track of:

For ActiveRecord:

class Article < ActiveRecord::Base
  include PublicActivity::Model

For Mongoid:

class Article
  include Mongoid::Document
  include PublicActivity::Model

For MongoMapper:

class Article
  include MongoMapper::Document
  include PublicActivity::Model

And now, by default create/update/destroy activities are recorded in activities table. This is all you need to start recording activities for basic CRUD actions.

Optional: If you don't need #tracked but still want the comfort of #create_activity, you can include only the lightweight Common module instead of Model.

Custom activities

You can trigger custom activities by setting all your required parameters and triggering create_activity on the tracked model, like this:

@article.create_activity key: 'article.commented_on', owner: current_user

See this entry http://rubydoc.info/gems/public_activity/PublicActivity/Common:create_activity for more details.

Displaying activities

To display them you simply query the PublicActivity::Activity model:

# notifications_controller.rb
def index
  @activities = PublicActivity::Activity.all

And in your views:

<%= render_activities(@activities) %>

Note: render_activities is an alias for render_activity and does the same.


You can also pass options to both activity#render and #render_activity methods, which are passed deeper to the internally used render_partial method. A useful example would be to render activities wrapped in layout, which shares common elements of an activity, like a timestamp, owner's avatar etc:

<%= render_activities(@activities, layout: :activity) %>

The activity will be wrapped with the app/views/layouts/_activity.html.erb layout, in the above example.

Important: please note that layouts for activities are also partials. Hence the _ prefix.


Sometimes, it's desirable to pass additional local variables to partials. It can be done this way:

<%= render_activity(@activity, locals: {friends: current_user.friends}) %>

Note: Before 1.4.0, one could pass variables directly to the options hash for #render_activity and access it from activity parameters. This functionality is retained in 1.4.0 and later, but the :locals method is preferred, since it prevents bugs from shadowing variables from activity parameters in the database.

Activity views

public_activity looks for views in app/views/public_activity.

For example, if you have an activity with :key set to "activity.user.changed_avatar", the gem will look for a partial in app/views/public_activity/user/_changed_avatar.html.(|erb|haml|slim|something_else).

Hint: the "activity." prefix in :key is completely optional and kept for backwards compatibility, you can skip it in new projects.

If you would like to fallback to a partial, you can utilize the fallback parameter to specify the path of a partial to use when one is missing:

<%= render_activity(@activity, fallback: 'default') %>

When used in this manner, if a partial with the specified :key cannot be located it will use the partial defined in the fallback instead. In the example above this would resolve to public_activity/_default.html.(|erb|haml|slim|something_else).

If a view file does not exist then ActionView::MisingTemplate will be raised. If you wish to fallback to the old behaviour and use an i18n based translation in this situation you can specify a :fallback parameter of text to fallback to this mechanism like such:

<%= render_activity(@activity, fallback: :text) %>


Translations are used by the #text method, to which you can pass additional options in form of a hash. #render method uses translations when view templates have not been provided. You can render pure i18n strings by passing {display: :i18n} to #render_activity or #render.

Translations should be put in your locale .yml files. To render pure strings from I18n Example structure:

    create: 'Article has been created'
    update: 'Someone has edited the article'
    destroy: 'Some user removed an article!'

This structure is valid for activities with keys "activity.article.create" or "article.create". As mentioned before, "activity." part of the key is optional.


For RSpec you can first disable public_activity and add require helper methods in the rails_helper.rb with:

require 'public_activity/testing'

PublicActivity.enabled = false

In your specs you can then blockwise decide whether to turn public_activity on or off.

# file_spec.rb
PublicActivity.with_tracking do
  # your test code goes here

PublicActivity.without_tracking do
  # your test code goes here


For more documentation go here

Common examples

Set the Activity's owner to current_user by default

You can set up a default value for :owner by doing this:

  1. Include PublicActivity::StoreController in your ApplicationController like this:
class ApplicationController < ActionController::Base
  include PublicActivity::StoreController
  1. Use Proc in :owner attribute for tracked class method in your desired model. For example:
class Article < ActiveRecord::Base
  tracked owner: Proc.new{ |controller, model| controller.current_user }

Note: current_user applies to Devise, if you are using a different authentication gem or your own code, change the current_user to a method you use.

Disable tracking for a class or globally

If you need to disable tracking temporarily, for example in tests or db/seeds.rb then you can use PublicActivity.enabled= attribute like below:

# Disable p_a globally
PublicActivity.enabled = false

# Perform some operations that would normally be tracked by p_a:
Article.create(title: 'New article')

# Switch it back on
PublicActivity.enabled = true

You can also disable public_activity for a specific class:

# Disable p_a for Article class

# p_a will not do anything here:
@article = Article.create(title: 'New article')

# But will be enabled for other classes:
# (creation of the comment will be recorded if you are tracking the Comment class)
@article.comments.create(body: 'some comment!')

# Enable it again for Article:

Create custom activities

Besides standard, automatic activities created on CRUD actions on your model (deactivatable), you can post your own activities that can be triggered without modifying the tracked model. There are a few ways to do this, as PublicActivity gives three tiers of options to be set.

Instant options

Because every activity needs a key (otherwise: NoKeyProvided is raised), the shortest and minimal way to post an activity is:

@user.create_activity :mood_changed
# the key of the action will be user.mood_changed
@user.create_activity action: :mood_changed # this is exactly the same as above

Besides assigning your key (which is obvious from the code), it will take global options from User class (given in #tracked method during class definition) and overwrite them with instance options (set on @user by #activity method). You can read more about options and how PublicActivity inherits them for you here.

Note the action parameter builds the key like this: "#{model_name}.#{action}". You can read further on options for #create_activity here.

To provide more options, you can do:

@user.create_activity action: 'poke', parameters: {reason: 'bored'}, recipient: @friend, owner: current_user

In this example, we have provided all the things we could for a standard Activity.

Use custom fields on Activity

Besides the few fields that every Activity has (key, owner, recipient, trackable, parameters), you can also set custom fields. This could be very beneficial, as parameters are a serialized hash, which cannot be queried easily from the database. That being said, use custom fields when you know that you will set them very often and search by them (don't forget database indexes :) ).

Set owner and recipient based on associations

class Comment < ActiveRecord::Base
  include PublicActivity::Model
  tracked owner: :commenter, recipient: :commentee

  belongs_to :commenter, :class_name => "User"
  belongs_to :commentee, :class_name => "User"

Resolve parameters from a Symbol or Proc

class Post < ActiveRecord::Base
  include PublicActivity::Model
  tracked only: [:update], parameters: :tracked_values
  def tracked_values
   {}.tap do |hash|
     hash[:tags] = tags if tags_changed?


Skip this step if you are using ActiveRecord in Rails 4 or Mongoid

The first step is similar in every ORM available (except mongoid):

PublicActivity::Activity.class_eval do
  attr_accessible :custom_field

place this code under config/initializers/public_activity.rb, you have to create it first.

To be able to assign to that field, we need to move it to the mass assignment sanitizer's whitelist.


If you're using ActiveRecord, you will also need to provide a migration to add the actual field to the Activity. Taken from our tests:

class AddCustomFieldToActivities < ActiveRecord::Migration
  def change
    change_table :activities do |t|
      t.string :custom_field

Assigning custom fields

Assigning is done by the same methods that you use for normal parameters: #tracked, #create_activity. You can just pass the name of your custom variable and assign its value. Even better, you can pass it to #tracked to tell us how to harvest your data for custom fields so we can do that for you.

class Article < ActiveRecord::Base
  include PublicActivity::Model
  tracked custom_field: proc {|controller, model| controller.some_helper }


If you need help with using public_activity please visit our discussion group and ask a question there:


Please do not ask general questions in the Github Issues.

Author: public-activity
Source code: https://github.com/public-activity/public_activity
License: MIT license

#ruby  #ruby-on-rails 

Why Use WordPress? What Can You Do With WordPress?

Can you use WordPress for anything other than blogging? To your surprise, yes. WordPress is more than just a blogging tool, and it has helped thousands of websites and web applications to thrive. The use of WordPress powers around 40% of online projects, and today in our blog, we would visit some amazing uses of WordPress other than blogging.
What Is The Use Of WordPress?

WordPress is the most popular website platform in the world. It is the first choice of businesses that want to set a feature-rich and dynamic Content Management System. So, if you ask what WordPress is used for, the answer is – everything. It is a super-flexible, feature-rich and secure platform that offers everything to build unique websites and applications. Let’s start knowing them:

1. Multiple Websites Under A Single Installation
WordPress Multisite allows you to develop multiple sites from a single WordPress installation. You can download WordPress and start building websites you want to launch under a single server. Literally speaking, you can handle hundreds of sites from one single dashboard, which now needs applause.
It is a highly efficient platform that allows you to easily run several websites under the same login credentials. One of the best things about WordPress is the themes it has to offer. You can simply download them and plugin for various sites and save space on sites without losing their speed.

2. WordPress Social Network
WordPress can be used for high-end projects such as Social Media Network. If you don’t have the money and patience to hire a coder and invest months in building a feature-rich social media site, go for WordPress. It is one of the most amazing uses of WordPress. Its stunning CMS is unbeatable. And you can build sites as good as Facebook or Reddit etc. It can just make the process a lot easier.
To set up a social media network, you would have to download a WordPress Plugin called BuddyPress. It would allow you to connect a community page with ease and would provide all the necessary features of a community or social media. It has direct messaging, activity stream, user groups, extended profiles, and so much more. You just have to download and configure it.
If BuddyPress doesn’t meet all your needs, don’t give up on your dreams. You can try out WP Symposium or PeepSo. There are also several themes you can use to build a social network.

3. Create A Forum For Your Brand’s Community
Communities are very important for your business. They help you stay in constant connection with your users and consumers. And allow you to turn them into a loyal customer base. Meanwhile, there are many good technologies that can be used for building a community page – the good old WordPress is still the best.
It is the best community development technology. If you want to build your online community, you need to consider all the amazing features you get with WordPress. Plugins such as BB Press is an open-source, template-driven PHP/ MySQL forum software. It is very simple and doesn’t hamper the experience of the website.
Other tools such as wpFoRo and Asgaros Forum are equally good for creating a community blog. They are lightweight tools that are easy to manage and integrate with your WordPress site easily. However, there is only one tiny problem; you need to have some technical knowledge to build a WordPress Community blog page.

4. Shortcodes
Since we gave you a problem in the previous section, we would also give you a perfect solution for it. You might not know to code, but you have shortcodes. Shortcodes help you execute functions without having to code. It is an easy way to build an amazing website, add new features, customize plugins easily. They are short lines of code, and rather than memorizing multiple lines; you can have zero technical knowledge and start building a feature-rich website or application.
There are also plugins like Shortcoder, Shortcodes Ultimate, and the Basics available on WordPress that can be used, and you would not even have to remember the shortcodes.

5. Build Online Stores
If you still think about why to use WordPress, use it to build an online store. You can start selling your goods online and start selling. It is an affordable technology that helps you build a feature-rich eCommerce store with WordPress.
WooCommerce is an extension of WordPress and is one of the most used eCommerce solutions. WooCommerce holds a 28% share of the global market and is one of the best ways to set up an online store. It allows you to build user-friendly and professional online stores and has thousands of free and paid extensions. Moreover as an open-source platform, and you don’t have to pay for the license.
Apart from WooCommerce, there are Easy Digital Downloads, iThemes Exchange, Shopify eCommerce plugin, and so much more available.

6. Security Features
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Hoang  Kim

Hoang Kim


14 Cách Hàng đầu để Lọc Khung Dữ Liệu Pandas Một Cách Dễ Dàng

Bất cứ khi nào chúng tôi làm việc với bất kỳ loại dữ liệu nào, chúng tôi cần một bức tranh rõ ràng về loại dữ liệu mà chúng tôi đang xử lý. Đối với hầu hết dữ liệu ngoài kia, có thể chứa hàng nghìn hoặc thậm chí hàng triệu mục nhập với nhiều loại thông tin, thực sự không thể hiểu được dữ liệu đó nếu không có bất kỳ công cụ nào để trình bày dữ liệu ở định dạng ngắn gọn và dễ đọc.

Hầu hết thời gian chúng ta cần xem qua dữ liệu, thao tác và trực quan hóa nó để có được thông tin chi tiết. Chà, có một thư viện tuyệt vời mang tên gấu trúc cung cấp cho chúng ta khả năng đó. Thao tác thao tác dữ liệu thường xuyên nhất là Lọc dữ liệu. Nó rất giống với mệnh đề WHERE trong SQL hoặc bạn phải sử dụng một bộ lọc trong MS Excel để chọn các hàng cụ thể dựa trên một số điều kiện.

pandas là một công cụ phân tích / thao tác dữ liệu nguồn mở, linh hoạt và mạnh mẽ, về cơ bản là mộtgói pythoncung cấp tốc độ, tính linh hoạt và cấu trúc dữ liệu biểu cảm được tạo ra để làm việc với dữ liệu “quan hệ” hoặc “có nhãn” một cách trực quan và dễ dàng. Nó là một trong những thư viện phổ biến nhấtđể thực hiện phân tích dữ liệu trong thế giới thực bằng Python.

pandas được xây dựng dựa trên thư viện NumPy nhằm mục đích tích hợp tốt với môi trường máy tính khoa học và nhiều thư viện bên thứ 3 khác. Nó có hai cấu trúc dữ liệu chính là Series (1D) Dataframe (2D) , trong hầu hết các trường hợp sử dụng trong thế giới thực là loại dữ liệu đang được xử lý trong nhiều lĩnh vực tài chính, máy tính khoa học, kỹ thuật và thống kê.

Hãy bắt đầu lọc dữ liệu với sự trợ giúp của khung dữ liệu Pandas

Cài đặt gấu trúc

!pip install pandas

Nhập thư viện Pandas, đọc tệp dữ liệu mẫu của chúng tôi và gán nó cho DataFrame “df”

import pandas as pd
df = pd.read_csv(r"C:\Users\rajam\Desktop\sample_data.csv")

Hãy kiểm tra khung dữ liệu của chúng tôi :


Dữ liệu mẫu

Dữ liệu mẫu

Bây giờ chúng tôi đã có DataFrame của mình, chúng tôi sẽ áp dụng nhiều phương pháp khác nhau để lọc nó.

Phương pháp - 1 : Lọc DataFrame theo giá trị cột

Chúng tôi có một cột tên là “Total_Sales” trong DataFrame của mình và chúng tôi muốn lọc ra tất cả giá trị bán hàng lớn hơn 300.

#Filter a DataFrame for a single column value with a given condition
greater_than = df[df['Total_Sales'] > 300]

Dữ liệu mẫu với doanh số> 300

Doanh số lớn hơn 300

Phương pháp - 2 : Lọc DataFrame dựa trên nhiều điều kiện

Ở đây chúng tôi đang lọc tất cả các giá trị có giá trị “Total_Sales” lớn hơn 300 và cũng có giá trị “Đơn vị” lớn hơn 20. Chúng tôi sẽ phải sử dụng toán tử python “&” thực hiện thao tác AND bitwise để hiển thị kết quả tương ứng.

#Filter a DataFrame with multiple conditions
filter_sales_units = df[(df['Total_Sales'] > 300) & (df["Units"] > 20)]

Hình ảnh 3

Lọc theo Doanh số và Đơn vị

Phương pháp - 3 : Lọc DataFrame dựa trên giá trị Ngày tháng

Nếu chúng tôi muốn lọc khung dữ liệu của mình dựa trên một giá trị ngày nhất định, ví dụ: ở đây chúng tôi đang cố gắng lấy tất cả kết quả dựa trên một ngày cụ thể, trong trường hợp của chúng tôi là kết quả sau ngày '03/10/21'.

#Filter a DataFrame based on specific date
date_filter = df[df['Date'] > '03/10/21']

Hình ảnh 1

Lọc vào ngày

Phương pháp - 4: Lọc DataFrame dựa trên giá trị Ngày với nhiều điều kiện

Ở đây, chúng tôi nhận được tất cả các kết quả cho hoạt động Ngày đánh giá nhiều ngày của chúng tôi .

#Filter a DataFrame with multiple conditions our Date value
date_filter2 = df[(df['Date'] >= '3/25/2021') & (df['Date'] <'8/17/2021')]

Hình ảnh 2

Lọc vào một ngày có nhiều điều kiện

Phương pháp - 5: Lọc DataFrame dựa trên một chuỗi cụ thể

Ở đây chúng tôi đang chọn một cột có tên là 'Khu vực' và lấy tất cả các hàng từ khu vực 'Đông', do đó lọc dựa trên một giá trị chuỗi cụ thể .

#Filter a DataFrame to a specific string
east = df[df['Region'] == 'East']

Hình ảnh 6

Lọc dựa trên một chuỗi cụ thể

Phương pháp - 6: Lọc DataFrame dựa trên một giá trị chỉ mục cụ thể trong một chuỗi

Ở đây chúng tôi đang chọn một cột có tên là 'Vùng' và lấy tất cả các hàng có ký tự 'E' là ký tự đầu tiên, tức là ở chỉ số 0 trong kết quả cột được chỉ định.

#Filter a DataFrame to show rows starting with a specfic letter
starting_with_e = df[df['Region'].str[0]== 'E']

Hình ảnh 7

Lọc dựa trên một chữ cái cụ thể

Phương pháp - 7: Lọc DataFrame dựa trên danh sách các giá trị

Ở đây chúng tôi đang lọc các hàng trong cột 'Vùng' chứa các giá trị 'Tây' cũng như 'Đông' và hiển thị kết quả kết hợp. Hai phương pháp có thể được sử dụng để thực hiện việc lọc này là sử dụng đường ống | toán tử với tập giá trị mong muốn tương ứng với cú pháp bên dưới HOẶC chúng ta có thể sử dụng hàm .isin () để lọc các giá trị trong một cột nhất định, trong trường hợp của chúng ta là 'Vùng' và cung cấp danh sách tập hợp mong muốn của các giá trị bên trong nó dưới dạng danh sách.

#Filter a DataFrame rows based on list of values
#Method 1:
east_west = df[(df['Region'] == 'West') | (df['Region'] == 'East')]
#Method 2:
east_west_1 = df[df['Region'].isin(['West', 'East'])]

Hình ảnh 9

Đầu ra của Phương pháp -2

Phương pháp - 8: Lọc các hàng DataFrame dựa trên các giá trị cụ thể bằng cách sử dụng RegEx

Ở đây chúng tôi muốn tất cả các giá trị trong cột 'Vùng' , kết thúc bằng 'th' trong giá trị chuỗi của chúng và hiển thị chúng. Nói cách khác, chúng tôi muốn kết quả của mình hiển thị các giá trị của "Nor th " và "Sou th " và bỏ qua "East" và "West" . Phương thức .str.contains () với các giá trị được chỉ định cùng với mẫu $ RegEx có thể được sử dụng để có được kết quả mong muốn.

Để biết thêm thông tin, vui lòng kiểm tra Tài liệu Regex

#Filtering the DataFrame rows using regular expressions(REGEX)
regex_df = df[df['Region'].str.contains('th$')]

Hình ảnh 10

Lọc dựa trên REGEX

Phương pháp - 9: Lọc DataFrame để kiểm tra null

Ở đây, chúng tôi sẽ kiểm tra các giá trị null và không null trong tất cả các cột với sự trợ giúp của hàm isnull () .

#Filtering to check for null and not null values in all columns
df_null = df[df.isnull().any(axis=1)]

Hình ảnh 12

Lọc dựa trên giá trị NULL hoặc NOT null

Phương pháp - 10: Lọc DataFrame để kiểm tra các giá trị null trong một cột cụ thể.

#Filtering to check for null values if any in the 'Units' column
units_df = df[df['Units'].isnull()]

Hình ảnh 13

Tìm giá trị null trên các cột cụ thể

Phương pháp - 11: Lọc DataFrame để kiểm tra các giá trị không rỗng trong các cột cụ thể

#Filtering to check for not null values in the 'Units' column
df_not_null = df[df['Units'].notnull()]

Hình ảnh 14

Tìm các giá trị not-null trên các cột cụ thể

Phương pháp - 12: Lọc DataFrame bằng cách sử dụng query()với một điều kiện

#Using query function in pandas
df_query = df.query('Total_Sales > 300')

Hình ảnh 17

Lọc các giá trị bằng QueryHàm

Phương pháp - 13: Lọc DataFrame bằng query()nhiều điều kiện

#Using query function with multiple conditions in pandas
df_query_1 = df.query('Total_Sales > 300 and Units <18')

Hình ảnh 18

Lọc nhiều cột với QueryHàm

Phương pháp - 14: Lọc DataFrame của chúng tôi bằng cách sử dụng các hàm lociloc.

#Creating a sample DataFrame for illustrations
import numpy as np
data = pd.DataFrame({"col1" : np.arange(1, 20 ,2)}, index=[19, 18 ,8, 6, 0, 1, 2, 3, 4, 5])

Hình ảnh 19

dữ liệu mẫu

Giải thích : iloc xem xét các hàng dựa trên vị trí của chỉ mục đã cho, do đó nó chỉ nhận các số nguyên làm giá trị.

Để biết thêm thông tin, vui lòng xem Tài liệu về Gấu trúc

#Filter with iloc
data.iloc[0 : 5]

Hình ảnh 20

Lọc bằng cách sử dụngiloc

Giải thích : loc xem xét các hàng dựa trên nhãn chỉ mục

#Filter with loc
data.loc[0 : 5]

Hình ảnh 21

Lọc bằng cách sử dụngloc

Bạn có thể đang suy nghĩ về lý do tại sao lochàm trả về 6 hàng thay vì 5 hàng. Điều này là do không tạo ra sản lượng dựa trên vị trí chỉ mục. Nó chỉ xem xét các nhãn của chỉ mục cũng có thể là một bảng chữ cái và bao gồm cả điểm đầu và điểm cuối. loc 

Sự kết luận

Vì vậy, đây là một số phương pháp lọc phổ biến nhất được sử dụng ở gấu trúc. Có nhiều phương pháp lọc khác có thể được sử dụng, nhưng đây là một số phương pháp phổ biến nhất.

Liên kết: https://www.askpython.com/python-modules/pandas/filter-pandas-dataframe

#pandas #python #datafame

田辺  亮介

田辺 亮介


輕鬆過濾 Pandas 數據框的 14 種方法


大多數時候,我們需要瀏覽數據、操作數據並將其可視化以獲得洞察力。嗯,有一個很棒的庫,它的名字叫 pandas,它為我們提供了這種能力。最常見的數據操作操作是數據過濾。它與 SQL 中的 WHERE 子句非常相似,或者您必須在 MS Excel 中使用過濾器來根據某些條件選擇特定行。

pandas是一個強大、靈活和開源的數據分析/操作工具,它本質上是一個python 包,提供速度、靈活性和富有表現力的數據結構,以直觀和簡單的方式處理關係”或“標記它是在 Python 中執行實際數據分析的最流行的庫

pandas建立在 NumPy 庫之上,旨在與科學計算環境和眾多其他第三方庫很好地集成。它有兩個主要數據結構,即Series (1D)Dataframes(2D),在大多數實際用例中,這是金融、科學計算、工程和統計等許多領域正在處理的數據類型。

讓我們開始在 Pandas Dataframe 的幫助下過濾數據


!pip install pandas

導入 Pandas 庫,讀取我們的示例數據文件並將其分配給“df” DataFrame

import pandas as pd
df = pd.read_csv(r"C:\Users\rajam\Desktop\sample_data.csv")





現在我們有了 DataFrame,我們將應用各種方法來過濾它。

方法 - 1:按列值過濾 DataFrame

我們的 DataFrame 中有一個名為“Total_Sales”的列,我們想要過濾掉所有大於 300 的銷售額。

#Filter a DataFrame for a single column value with a given condition
greater_than = df[df['Total_Sales'] > 300]

銷售額 > 300 的 Sample_data

銷售額超過 300

Method – 2 : Filtering DataFrame based on multiple conditions

在這裡,我們過濾“Total_Sales”值大於 300 以及“Units”大於 20 的所有值。我們將不得不使用執行按位與操作的 python 運算符“&”以顯示相應的結果。

#Filter a DataFrame with multiple conditions
filter_sales_units = df[(df['Total_Sales'] > 300) & (df["Units"] > 20)]

圖 3


方法 – 3:根據日期值過濾 DataFrame

如果我們想根據某個日期值過濾我們的數據框,例如這裡我們試圖獲取基於特定日期的所有結果,在我們的例子中是日期 '03/10/21' 之後的結果。

#Filter a DataFrame based on specific date
date_filter = df[df['Date'] > '03/10/21']

圖 1



在這裡,我們得到了評估多個日期的 Date 操作的所有結果。

#Filter a DataFrame with multiple conditions our Date value
date_filter2 = df[(df['Date'] >= '3/25/2021') & (df['Date'] <'8/17/2021')]

圖 2




#Filter a DataFrame to a specific string
east = df[df['Region'] == 'East']

圖 6


方法6:根據字符串中的特定索引值過濾 DataFrame

在這裡,我們選擇一個名為“Region”的列,並獲取所有以字母“E”作為第一個字符的行,即指定列結果中索引 0 處的所有行。

#Filter a DataFrame to show rows starting with a specfic letter
starting_with_e = df[df['Region'].str[0]== 'E']

圖 7


方法7:根據值列表過濾 DataFrame

在這裡,我們過濾包含值“West”和“East”的“Region”列中的行,並顯示組合結果。可以使用兩種方法來執行此過濾,即使用管道 | 具有相應所需值集的運算符具有以下語法,或者我們可以使用.isin()函數過濾給定列中的值,在我們的例子中是“區域”,並提供所需集的列表它裡面的值作為一個列表。

#Filter a DataFrame rows based on list of values
#Method 1:
east_west = df[(df['Region'] == 'West') | (df['Region'] == 'East')]
#Method 2:
east_west_1 = df[df['Region'].isin(['West', 'East'])]

圖 9


方法 – 8:使用 RegEx 根據特定值過濾 DataFrame 行

在這裡,我們想要列 'Region' 中的所有值,並在其字符串值中以 'th'結尾並顯示它們。換句話說,我們希望我們的結果顯示 'Nor th ' 和 'Sout th ' 的值並忽略 'East' 和 'West'。具有指定值的方法.str.contains()以及$ RegEx 模式可用於獲得所需的結果。


#Filtering the DataFrame rows using regular expressions(REGEX)
regex_df = df[df['Region'].str.contains('th$')]

圖 10

基於 REGEX 的過濾器

方法9:過濾 DataFrame 以檢查null

在這裡,我們將在isnull() 函數的幫助下檢查所有列中的空值和非空值。

#Filtering to check for null and not null values in all columns
df_null = df[df.isnull().any(axis=1)]

圖 12

基於 NULL 或 NOT 空值過濾

方法 - 10:過濾 DataFrame 以檢查特定列中的空值。

#Filtering to check for null values if any in the 'Units' column
units_df = df[df['Units'].isnull()]

圖 13


方法 – 11:過濾 DataFrame 以檢查特定列中的非 空值

#Filtering to check for not null values in the 'Units' column
df_not_null = df[df['Units'].notnull()]

圖 14


Method – 12: Filtering DataFrame using query()with a condition

#Using query function in pandas
df_query = df.query('Total_Sales > 300')

圖 17


Method – 13: Filtering DataFrame using query()with multiple conditions

#Using query function with multiple conditions in pandas
df_query_1 = df.query('Total_Sales > 300 and Units <18')

圖 18


方法 –loc 14:使用和iloc函數過濾我們的 DataFrame 。

#Creating a sample DataFrame for illustrations
import numpy as np
data = pd.DataFrame({"col1" : np.arange(1, 20 ,2)}, index=[19, 18 ,8, 6, 0, 1, 2, 3, 4, 5])

圖 19


解釋iloc 根據給定索引的位置考慮行,因此它僅將整數作為值。

有關更多信息,請查看Pandas 文檔

#Filter with iloc
data.iloc[0 : 5]

圖 20


說明loc 考慮基於索引標籤的行

#Filter with loc
data.loc[0 : 5]

圖 21


您可能正在思考為什麼loc函數返回 6 行而不是 5 行。這是因為不會根據索引位置產生輸出。它只考慮索引標籤,它也可以是字母表,包括起點和終點。 loc 


因此,這些是 pandas 中最常用的一些過濾方法。還有許多其他過濾方法可以使用,但這些是最常見的一些。

鏈接:https ://www.askpython.com/python-modules/pandas/filter-pandas-dataframe

#pandas #python #datafame