02Jul

How to Use Comments in Python 3?

July 2, 2022 admin

It happens with every programmer, be it an expert or a novice, that you need to go back to the code you wrote and make changes in it. When you are writing a small code, for example, adding two numbers, the program is a child’s play. You can do it with the snap of a finger. But what about a complex program on which your entire team is working day and night? What if you need to go over the entire code? It looks like nothing but a mess.

Many people have worked on the code and you can’t understand why the programmer wrote it. In such a situation, comments come to your aid. These are small explanations that tell everyone why a code is written in a particular way, and what does it signify. Making comments while writing the code or immediately after writing the program can be very helpful as what you wrote is still fresh in your mind.

Python is a programming language that has gained popularity among programmers and many programs have been written using it. It is a language that is simple and thus programmers use it on a large scale, thus, the question always arises as to how to use comments in Python 3.

In this blog, we will discuss various kinds of comments that you can use in Python 3. So hop on.

Why Writing Comments in Python 3 is Important?

Before asking how to write comments in Python 3, you must understand its importance. The benefits of writing comments in Python 3 are:

Better Understandability: If a beginner looks at your code, he/she must be able to understand it. If they are going to work alongside you or take your work further, they must know what is going on in code. Explanatory comments provide better understandability even to those who are not experts in programming.
To Make Quicker Change: If you look at your written program after a while, it will take too much of your time only to read and understand it. With proper comments, you can understand your program, make quicker changes, and save a lot of time.
It is a Good Habit: If there is a concept called good coding habit, writing comments fall under that criteria. When you keep writing comments as you use the code, it proves to be very helpful in the long run.

How to Use Comments in Python 3?

Comments in Python 3 are not of a single type that works for every situation. People may confuse using comments in Python 3 with adding comments in a shared document. But these are different. Every comment has a purpose, and there is a proper way of writing it, which you will learn here.

1. Syntax of a Comment

First of all, you must know the syntax of a comment, i.e. the format in which a comment is written. It always starts with a hash, followed by a whitespace character. So, a simple comment is written as:

# Hello!

You don’t execute a comment. It is not part of a program. You can take it as a backend thing that is meant for human use and not for computers to read it and execute it. A comment is not deployed when a program is written.

So, in a simple program, it will look like this:

# Print “Hey, Buddy!” to console

print (“Hey, Buddy!”)

In an iterating loop, e.g. a loop, the comment will look like:

water.py

# Define water variable as strings

water = [‘sparkling’, ‘Chilled’, ‘Tap’, ‘Normal’]

# for loop that iterates over water list and prints

each string item

for water in waters

print (water)

Remember, a comment is indented in the same way as the code for which it is written. To understand the indentation, you can go over the again function in this Calculator Program.

…

# Define again() function to check with user if they want to use the program again

def again():

# Take input from user

calc_again = input(”’

Do you want to use the program again?

Please choose between Y/N for Yes and No.

”’)

# If user types Y, use the program again

if calc_again == ‘Y’:

calculate()

# If user types N, Exit the program after saying goodbye to user

elif calc_again == ‘N’:

print(‘See you later.’)

# If user types another key, run the function again

else:

again()

You must understand the essentials and importance of a comment to maintain its worth. It is not just the creator of the program, who uses the comment, but others as well. If you don’t use it in alignment with the code, there is no point in writing it as it will only cause more confusion. The comment is supposed to be simple and not an explanatory one describing what and how of the code but an answer to a simple ‘why’.

2. Block Comments

These comments are used when the code is not a regular one but a complicated one that needs a good comment. The indentation and syntax rules are the same for block comments as well.

As they are long comments, you need to write each line starting with a hash mark. In case of more than one paragraph, separate it by a line.

You can go over this example of a block comment explaining the main () function.

# The main function will parse arguments via the parser variable. The

# use will define the arguments. This will forward the word arguments and

# the filename user wants to use, and in case of wrong argument

# it will pop up the text file.

def main():

parser = argparse.ArgumentParser()

parser.add_argument(

“word”,

help=”look for this word in the file.”

)

parser.add_argument(

“filename”,

help=”the path to the text file to be searched through”

)

…

When you are writing complex code, block comments can be very useful but that doesn’t allow you to stuff the code with comments. Leave room for other programmers to understand it. Write only what is necessary.

3. Inline Comments

When your comment is written in the same line as the concerned code, it is called an inline comment. It also follows the syntax and looks like this:

[code] # Inline comment for the code

When you are writing a lengthy program and a complex one on top of that, in such a case, you need inline comments to explain the difficult or tricky parts. If you think this line of code is important and you will need to go over it in the future, or if you want to highlight it for your team, this comment will come in handy.

For example, if you have written a program that does not contain anything about a complex number but a line of code returns a complex number, you can highlight it by an inline comment for your team members.

x = 5.8+ 4j # Create a complex number

You can insert it as an explanation or additional information as to why you did that.

x = 8 # Initialize x with an arbitrary number

Use the inline comments after carefully thinking.

4. Commenting Out Code

When you write or debug a program, you can check it a thousand times. You can try certain permutations and combinations to find out which line of code is causing the problem. You can’t simply delete a line of code to execute the program. You can comment it out i.e. exclude a line of code while testing the program.

You can use comments to resolve this. The comments can help you decide between loops as well as a while loop and for a loop.

Here’s an example to understand it:

import random

number = random.randint(1, 20)

# user’s_guess_number = 0

for i in range(6):

# while user’s_guess_number < 6:

print(‘Guess a number between 1 and 20:’)

guess = input()

guess = int(guess)

# user’s_guess_number = user’s_guess_number + 1

if guess < number:

print(‘You guessed a lower number’)

if guess > number:

print(‘You guessed a higher number’)

if guess == number:

break

if guess == number:

print(‘You have guessed the correct number!’)

else:

print(‘You did not guess the correct number. It is ‘ + str(number))

It is a simple way of finding out the problem section in your program.

Conclusion

Coding is fun. Writing programs is amazing. Being a programmer, you invest hours in writing every single function, action, and instruction of a program. Any problem in any part of the program cannot be tolerated. Thus, it is essential to check every line carefully as a problem can lie anywhere.

As you work in a team, your fellow members, even you should understand the reason behind writing a particular line or program. Comments are a way to help it. You can add an answer to “why” in a single line, you can add a block comment for a complex one, an inline comment to describe a tricky line or you can take help of a comment out code as you are testing or debugging.

This guide covers every kind of comment you can use in Python 3. Hopefully, it has answered your question about how to use comments in Python 3.

25Jun

How to Get the Current Date and Time in Python?

June 25, 2022 admin

When you are working on a program, how do you get the current time and date? The answer is simple. You use a Data type, and it gets your current date and time in a matter of seconds. But, it’s not how it works for Python.

Then how to get the current date and time in Python? In Python, if you want to get the date and time, there is no data type for it. There is a separate module called the datetime module. To get the current date and time, you have to use it. Getting the current date and time is easy in Python and can be performed using several functions provided that you have the module.

For working with time and date, there are different date objects. The date is returned in several formats, including year, day, month, minutes, hours, and seconds. This function requires the year, day, and month values and returns the output in the desired format.

This guide will help you learn how to get the current date and time in Python using the datetime module. You will learn how you can use several different functions to get the date and time.

Prerequisites To Get Current Date And Time

What you need here is-

Root user with sudo privileges
Access to command line window
A text editor such as nano

How To Get Current Date And Time In Python Using Different Functions

Now you will learn how to get the current date and time in Python using different functions as there are several ways to get it.

Using today() function

Create and access a new file with – sudo nano python_date.py
Since you don’t have the file, you are asked to create it. So click yes and type:

– from datetime import date

today = date.today()

print(“Today’s date:”, today)

Save and exit. Now run the file with – python python_date.py
It will return the result that will look like – python python_date.py

( ‘Todays date: ‘ , ‘datetime.date (2021.06.29))

It picks up today’s date and returns it in yyyy-mm-dd format.

Using strftime()

It returns the output using date, time, and datetime objects.

Getting current time using strftime()

Enter the command – sudo nano python_time.py
Use this file, and define how you want the time to display-

import time

print (time.strftime(“%H:%M:%S”))

Save the file and run the following command to get the current time-

python python_time.py

The result will look like-

python python_time.py

17:15:23

If you want the result to display in a 12-hour format, you must change the command as-

import time

print (time.strftime(“%I:%M:%S”))

Then execute the command normally and the result will be displayed in a 12 hour format.

Getting Current Date And Time Using now() function

Another part of the datetime module is now() function which produces the date and time in yyyy-mm-dd hh:mm:ss ms format.

Getting current date and time

from datetime import datetime

current_date = datetime.now()

print(“Current Date and Time=”, current_date)

string = current_date.strftime(“%d/%m/%Y %H:%M:%S”)

print(“Current Date and Time in different format=”, string)

The result will be something like-

Current Date and Time= 2021-06-29 17:15:29.633526

Current Date and Time in different format= 29/06/2021 17:15:29

Getting Current Time

from datetime import datetime

current_time = datetime.now().time()

print(“Current Time:”, current_time)

The result will look like-

Current Date: 17:16:39.372822

Formatting The Date And Time Format

You can also define datetime formatting and ask the system to display the date and time In a particular format.

Using Datetime Object

Type the following to create a sample file-

sudo nano sample_format.py

Now edit the file-

import datetime

e = datetime.datetime.now()

print (“Current date and time = %s” % e)

print (“Today’s date: = %s/%s/%s” % (e.day, e.month, e.year))

print (“The time is now: = %s:%s:%s” % (e.hour, e.minute, e.second))

Save and exit. Run the following command-

python sample_format.py

You will get the answer in three different lines as per the defined format.

python sample_format.py

Current date and time = 2021.06.29 17.15.29.563178

Today’s date – 29/6/2021

The time is now – 17.15.29

Using strftime() function

Here, today() function is used to store date in variable and strftime() is used to print date in different formats-

from datetime import date

current_date = date.today()

date1 = current_date.strftime(“%d/%m/%Y”)

print(“Date in date/month/year format =”, date1)

date2 = current_date.strftime(“%B %d, %Y”)

print(“Date in month/day/year format =”, date2)

date3 = current_date.strftime(“%m/%d/%y”)

print(“Date in month/date/year format =”, date3)

date4 = current_date.strftime(“%b-%d-%Y”)

print(“Date in month/date/year format =”, date4)

It will display the output as-

Date in Date/Month/Year format = 18/01/2021

Date in Month Name Date, Year format = January 18, 2021

Date in Month/Date/Year format = 01/18/21

Date in Month-Date-Year format = Jan-18-2021

Using datetime.now() function

Using tz parameter, you can get current time and date of a particular timezone, which Greenwich meridian by default-

# Python3 code to demonstrate

# Getting current date and time using

# now().

# importing datetime module for now()

import datetime

# using now() to get current time

current_time = datetime.datetime.now()

# Printing value of now.

print (“Time now at greenwich meridian is : ” , end = “”)

print (current_time)

It will return the output as-

Time now at greenwich meridian is : 2021-06-29 17:16:58.967356

The now() function as different attributes which it can display-

# Python3 code to demonstrate

# attributes of now()

# importing datetime module for now()

import datetime

# using now() to get current time

current_time = datetime.datetime.now()

# Printing attributes of now().

print (“The attributes of now() are : “)

print (“Year : “, end = “”)

print (current_time.year)

print (“Month : “, end = “”)

print (current_time.month)

print (“Day : “, end = “”)

print (current_time.day)

print (“Hour : “, end = “”)

print (current_time.hour)

print (“Minute : “, end = “”)

print (current_time.minute)

print (“Second : “, end = “”)

print (current_time.second)

print (“Microsecond : “, end = “”)

print (current_time.microsecond)

The output will display the attributes as-

The attributes of now() are :

Year : 2021

Month : 06

Day : 29

Hour : 17

Minute : 18

Second : 12

Microsecond : 292616

Getting Time of Your Timezone

You can define the code to get the date and time of your timezone. The pytz library has timezones defined and now() takes input of timezone and gets you the current date and time of your output.

# Python3 code to demonstrate

# attributes of now() for timezone

# for now()

import datetime

# for timezone()

import pytz

# using now() to get current time

current_time = datetime.datetime.now(pytz.timezone(‘Asia/Kolkata’))

# printing current time in India

print (“The current time in India is : “)

print (current_time)

The result will look like-

The current time in India is :

2021-06-29 17:58:23.973616+05:30

Final Words

Python is a very interesting programming language. The functions are amazing and you can enjoy managing different combinations using different functions. Getting the current date and time is one of the simplest functions but there are many ways to get it. In this guide, you get various answers to how to get the current date and time in Python.

Using today(), strftime(), and now(), you will learn how to obtain the current date and time. Using the above functions, you can get results in different formats. You also learned how to get the current date and time of your timezone. Each date and time format combination can be made in any combination you wish, so there is no limit to how many you can try out.

20Jun

How to Install PIP to Manage Python Packages on Windows?

June 20, 2022 admin

When it comes to managing Python packages on Windows, you need to learn a lot before downloading PIP. PIP, commonly known as Preferred Installer Program, is a Python package installer.

Manually downloading, installing, and managing packages can be time-consuming and irritating. In order to simplify things considerably, many Python developers use a custom tool called PIP for Python (or Python PIP).

Basically, you tell PIP what package you want to install, and it downloads and installs it, so that it can be used by the Python language on your computer. It is important to remember that the programs will still need to import the package in order to use it – PIP ensures that it is ready to import.

PIP is included by default in Python versions 3.4 and above. PIP’s command-line interface (CLI) offers a significant advantage in that it allows Python software packages to be installed seamlessly as if they were a command.

What are Python Packages?

Programmers love Python. It is a swift and simple to use programming language. Python saves a lot of development time with its simple-to-read syntax and easy compilation trait. Python is a typical programming language, which means that it can be used for more than just web development, unlike HTML, CSS, and JavaScript. This includes, among other things, software development and back-end development.

Python’s built-in debugger makes debugging your scripts a breeze. Using Python increases programmers’ productivity and, as a result, the quality of their applications. Python is a widespread preference among data scientists for generating and deploying machine learning applications as well as other scientific computations.

Python is available for Windows, Linux/Unix, and Mac OS, and it has been converted to .NET and Java virtual tools. Python is free of cost even for commercial gains, thanks to an open-source license approved by the OSI.

Python has developed into the ultimate favoured language for data analytics. The increasing search patterns for python also show that Python is the future “Big Thing” and a must for Data Analytics Professionals.

Like any other significant programming language, Python allows third-party libraries and frameworks that you may install to avoid having to repeat history with each new project. If you want to employ them, you may locate them in a central repository known as the Python Package Index (PyPI). Using a Pip, you’ll install the packages from PyPI only.

Prerequisites to Install PIP on Windows:

Ascertain if your system is running Windows or Windows server.
Unless you installed an older version of Python, the Python installer should have installed PIP, and it should be ready for use.
Run a command prompt window:

Click on the Windows Key + X > Hit Run > Type in cmd.exe > Press enter.

Run the following command in your prompt to see if PIP is available:

pip –version

This particular command will also let you see which version of PIP is installed in your system.

How to Download Pip on Windows?

Trust me if you’ve come so far. This is going to be a cakewalk for you.

Download and save the get-pip.py file in the same location where Python is installed.
Launch the command prompt
Reach the folder that comprises the file
And run the following command

Python get-pip.py

Press enter, and Voila! PIP will be installed in your system in an instant.
Another approach is to install PIP on Windows. On the other hand, you can verify if pip is installed in your system by following the steps below:

Open the command prompt > put the command pip install PIP > and enter.

Congrats on the installation. Now, let us tell you how you can utilize PIP to install a library.

Open the terminal
Run the following command:

pip install (followed by the name of the library)

For example:

pip install panda

And this particular library will be installed in your system in no time.

How to Configure Pip on Windows?

The configuration file on Windows is %APPDATA%\pip\pip.ini.

Using the environment variable ‘PIP_CONFIG_FILE,‘ you can specify a different location for this configuration file.

Now, to upgrade the current version of PIP that you’re using, you’ll again have to follow some easy steps:

Open command prompt > feed the command: Python -m pip install –upgrade pip > press enter.

This particular command will uninstall the previous command and install the latest version of PIP that is available.

Sometimes, even the latest version cannot be beneficial to you. In that case, you might need a previous version that will go well with your system.

To do this, you’ll have to use the following command in your terminal:

python -m pip install pip==version_number

The version number stands for your desired version of PIP. Whichever version you need, just feed in the number, and that is it. You’ll be able to use that particular version after running this command.

Conclusion

That’s all! Now you know how to install Pip to manage Python packages on Windows PC. Well, there are instances when this installation process failed due to a variety of reasons.

In many cases, contacting the package developer is the best answer. Attempting to install in a location where you do not have the authorization to change is a common source of problems. For instance, the default install location may necessitate Administrative capabilities, but Python does not have them by nature. The ideal solution is to install it in a virtual environment.

Native code in some packages requires the installation of a C or C++ compiler. Although package providers should, in principle, publish precompiled versions, they rarely do. You may be able to use some of these packages if you install Build Tools for Visual Studio and select the C++ option. In almost every case, you will need to contact the package’s developer.

26Jan

How to Install Flask and Create Web Applications?

January 26, 2022 admin

If you are a beginner in web application development, you may want to start out with Python’s flask because it is easy to follow. In Python, there are many web application frameworks and Flask provides the quickest and easiest way to develop your applications. Flask is a microframework that offers many features and tools, making it easy to apply while being suitable for complex projects. In this article, we will show you how to install flask and build a web application.

What Do You Need to Install Flask?

In the Flask Micro Web framework, you will find many important tools, libraries, and technologies that will help you build web pages as well as e-commerce applications. However, when beginner developers are learning backend web development, they often have a hard time selecting the suitable framework option. Flask’s simplicity makes it easy for beginners to learn. We will discuss how to install Flask on your virtual environment shortly. Here are some elements to consider before moving on:

Install Python 2.7 or Python 3.5 or any later version of Python
You will need CLI with admin privileges.

If you have installed Python and have the command-line interface, then let’s look at the steps of installing Flask on your computer. But we have also discussed above how you can install the virtual environment and activate it before installing Flask. So, let’s look at that first.

Step 1: Install Python

We have already stated above that you need Python 2.7 or 3.5 to install Flask. Hence, you need to check out the version of Python your system is already running. If the python version is incompatible with Flask then it will have conflicts with the libraries. If you are using Python 2, you need to install the virtualenv module because Python 2 does not come with that by default. But Python 3 users can skip the virtualenv installation. Here we have demonstrated how you can install the ‘virtualenv’ module on your Linux, Mac, and Windows.

To Install the Virtualenv Module on Linux

Linux package manager has virtualenv and you can easily install that by applying a few commands. If you are running Ubuntu or Debian, you can run this command on your terminal:

sudo apt install python-virtualenv

If you are using CentOS or Fedora, or Red Hat, you can enter this command on your terminal:

sudo yum install python-virtualenv

And the command will install the existing virtualenv package on your Linux system.

To Install virtualenv on Mac OS and Windows

To install virtualenv on Mac, open your terminal and run the following command to install the package:

sudo python2 -m pip install virtualenv

To install it on Windows

Windows does not have a terminal and to install virtualenv, you will have to run a simple command on its Command-line prompt that has administrator access. Run this command on the Command line.

py -2 -m pip install virtualenv

Once you learn how to install Python, you need to create a virtual environment. The following steps will teach you how to set up a virtual environment on various operating systems.

Step 2: Formulate a Virtual Environment

To install Flask, you will create an individual directory with a command: mkdir <project name>

To move into the above directory, use this command:

cd <project name>

A virtual environment of Flask can be created in that directory. As soon as you design the background, you will find a unique folder in the directory with the same name as your environment. To create an environment for Python 3 on a Linux or Mac computer, you must give the venv module a name with the following command:

python3 -m venv <name of environment>

If your system is running Python 2, then you can apply the virtualenv module and create an environment and give it a name.

python -m virtualenv <name of environment>

To form an environment in Windows, for Python 3, design and define a virtual environment with the following command:

py -3 -m venv <name of environment>

As to python 2, design the background by the virtualenv module:

py -2 -m virtualenv <name of environment>

Now, insert the folder construction utilising the following command:

dir *<project name>*

Your project directly will show you the recently created virtual environment on Python and your next step will be to activate the environment. To install Flask, you need to activate the environment first.

Step 3: Initiate the Environment

Initiate the environment with the following commands for different operating systems. The newly activated environment name will appear in the CLI following activation.

To activate the environment in Mac OS and Linux:

. <name of environment>/bin/activate

To activate the environment in Windows:

<name of environment>Scriptsactivate

After the activation is complete, you can Install Flask on your system. The Flask installation process comes with a few steps. Follow the section below to learn about them.

Step 4: Establish the Flask

The first step of installing flask includes creating a directory for Flask and you can use the following command for that:

$ mkdir flask_website

Change the directory to the Flask_website directory:

$ cd flask_website

We have already stored the tools of the environment in the env folder but if you have missed that step, let’s do it now:

$ python3 -m venv env

Now, install Flask by running this command:

(env)$ pip install flask

Your Flask will be installed on its own by all its dependencies. When it’s done, the next step will be to test the development environment.

Step 5: Analysis of the Development with a Flask Application

Create a new file in the Flask project folder and rename it with hello.py and edit that file with a text editor.
While you are editing the file, you should attach the resulting codes so that it becomes a statement that reprints “Hello world!”:

from flask import Flask

app = Flask(__name__)

@app.route(‘/’)

def hello_world():

return ‘Hello world!’

Save the new file and exit the editor.
And navigate where the project folder is with the cd command from the console. Here you will have to configure the FLASK_APP environment variable.
Setting the environment variable for flask requires a command which is different for Linux or Mac and Windows systems.
For Linux and Mac, apply the following command:

export FLASK_APP=hello.py

For Windows system, perform the following command:

setx FLASK_APP “hello.py”

Now if you operate the Flask software, you can run the following command:

flask run

The output will show you a verification report and also will show you an address. Copy that address and search for it in the browser and you will see that your Flask project is running.

Conclusion

You can also structure your web application using a few commands and using the requirement.txt file. The “requirement.txt” file will be there in the app folder and will help you define the flexibility of your Flask application. A flexible flax application package will be suitable for importing in any part of the web application. And on the other hand, the run.py file works as the pointer to Flask that informs Flask where the application is and helps it run the web application. Additionally, the requirement.txt file stores all of the project’s packages. The requirement.txt file can be created by running (env)$ pip freeze > requirements.txt. The requirement file will list all the packages used in Flask but there won’t be more than seven packages.

So, that’s basically how you create an environment for Flask and install it and operate it on your computer. To know more about this or for additional questions, you can drop us a comment below with your queries.