DEV Community: importostar

Which is better, Python or C++?

importostar — Tue, 07 Jul 2020 10:44:28 +0000

Between Python and C++ you can't answer which is better because programming languages are like tools. So that's like asking what's better a pen or a pencil?

If you want to develop high level apps, like web apps, video games, desktop apps, machine learning or basic scripting then you can go for Python

If you want to do operating system development or electronics programming, you can use for C.

So it depends on the application domain. So for C is more low level stuff, and Python is more what the end user touches.

Which database is suitable for Python Flask?

importostar — Tue, 07 Jul 2020 10:36:49 +0000

Learn Flask, Python Web Development

Flask is a micro framework, this means you can develop your app but you're not forced into a certain architecture like django does.

So you can use any database system like sqlite, mysql or even an object relational manager, but you don't have to. You are free to create your own app design, you can even chose not to use a database at all.

You can add any Python modules to your Python Flask web app!

How to build websites with Python

importostar — Tue, 07 Jul 2020 10:30:01 +0000

Learn Flask, Python Web Development

This explains how to build Python web apps, how to deploy it, how to do routing, templates etc. This will really improve your Python skills.

A module that lets you do that is the Flask module. Large companies are using Python Flask in order to create their web apps, so you don't have to worry about scale to much. You can use it to build a web app or an API

If you want to make websites or web apps with Python you can with Flask.

How to debug a Flask app?

importostar — Tue, 07 Jul 2020 10:23:24 +0000

Learn Flask, Python Web Development

If you want to debug your Python Flask app, that's easy to do. So what you want to do is, in your app object add the parameter debug is true.

app.run(debug=True)

The app then outputs a lot more data. All of the data is shown in the terminal.

For more Python debugging, you can reference this article https://pythonspot.com/python-debugging/

What is Python Flask?

importostar — Tue, 07 Jul 2020 10:05:58 +0000

Learn Flask: https://gumroad.com/l/IMzBy

If you want to make web apps in Python, like a SaaS. You can. There are several frameworks to chose from like Tornado, web2py, Django and Flask. Flask is a module (framework) for Python. You can use this module to build your web apps.

You can link any web url to a Python function, and the output of that Python function is shown to you in the browser. You can output strings, but you can also output templates. Data can be added to a template, and show in a nice format. Flask uses the Jinja2 template engine.

Flask gives you a lot of freedom in terms of designing your app. You can just load the Flask module and add any other modules you want. Unike Django that forces you to use an ORM etc. Flask lets you add what you want, so you are free to add a database, orm (or not) etc.

Learn Flask for Webdev

importostar — Sat, 27 Jun 2020 09:49:10 +0000

Flask is a Python framework that you can use to make Web Apps with Python. Python doesn't have to be only in the terminal, you can create any web app with Python Flask.

This is a collection of articles to help you get started with the Python Flask framework.

What is Flask?

First Apps

Advanced

import keyword with example in Python

importostar — Sat, 27 Jun 2020 09:31:41 +0000

Python import keyword: so you can know about the import keyword with example.

Its used to get modules and a module is like a building block: it has many functions available. You can use pip to install modules.

Python import keyword

import is a python keyword used to import module in a script

Syntax of import keyword

    import module_name

Python Example:

    import math
    # this will load the math module

Python examples of import keyword

Import the math module in this script and call a function

import math
num = 5

# call function in module
result = math.factorial(num)

# print output
print("The factorial of ", num, " is = ", result)

The program above outputs this:

The factorial of  5  is =  120

Example 2:

Module load datetime and name the present day, month and year

import datetime

# create date object
dt = datetime.datetime.now()

# get day, month and year
print("day  : ", dt.day)
print("month: ", dt.month)
print("year : ", dt.year)

The program above outputs this:

day  :  27
month:  7
year :  2020

You can use modules to add all kinds of functionality to your program. Using modules could create a canvas, gui with pyqt, bmi calculator, web app etc. You can create modules if you want.

tkinter gui

importostar — Fri, 26 Jun 2020 08:30:42 +0000

You learn the basic idea of the Python GUI programming via the tkinter module in this post. This tutorial is mainly designed to understand the simple tkinter concept that allows you to build any Python GUI.

GUI: GUI is a basic program that allows users to communicate with their machine through a graphical interface.

GUI tkinter module

tkinter is a built-in Python framework for GUI development.

Python offers a variety of GUI choices like tkinter, pyqt and others.

The most popular way to create a graphical application is tkinter.

Apps are constructed like this:

Import the tkinter module
Build the window of the GUI application
In the main window of a Interface program, add some amount of widgets
Start the main loop

import tkinter as tk
from tkinter import *

Example = tk.Tk()

rad1=Radiobutton(Example, text='Content', value=1)
rad1.pack()
rad2=Radiobutton(Example, text='Software', value=2)
rad2.pack()
label=Button(Example,text='Welcome to Example', width=100)
label.pack()


Example.mainloop()

.mainloop() when ready to run a program. This shows the window until it's closed.

Widgets can be placed in 3 ways:

pack():
the widgets put in the widget parent.
grid():
the grid widgets are put in the parent widget.
place():
positions them at different points that we control.

Tkinter lets you place all kinds of widgets like buttons, radiobuttons, listbox etc.

# button
button_name=tkinter,Button(
       parent,  
       text='your text', 
       width='width_of_text', 
       command='function to call')

# radio button    
rad1=Radiobutton(
       parent, 
       text='your text', 
       value=numerical_value).pack()

# listbox
List=Listbox(parent)
List.insert(1, text)
List.insert(2, nexttext)

# Entry
label1=Label(parent, text='Name').grid(row=0)
label2=Label(parent, text='password').grid(row=1)
entry_in_label1 = Entry(parent)
entry_in_label2 = Entry(parent)
entry_in_label1.grid(row=0, column=1)
entry_in_label2.grid(row=1, column=1)

You can make a GUI for any type of code, like a bmi calculator, notifications, progressbar, canvas etc.

If you are new to tkinter, I recommend this course

python list directory files

importostar — Mon, 22 Jun 2020 21:19:52 +0000

Do you want to find out how to display all directory's files using Python?

You can use os.walk() or glob() in the Python programming language.

To list files and folders you can use os.walk(). From there you can do specific file handling

Did you know Python can download files from the web?

List files and folders

os.walk()

List all the Python files in the directory
and subdirectories:

import os                                                                       
files  = []                                                                     
cwd = os.getcwd()                                                               
# (r)oot, (d)irectory, (f)iles                                                  
for r,d,f in os.walk(cwd):                                                      
    for file in f:                                                              
        if '.py' in file:                                                       
            files.append(os.path.join(r,file))                                  

for f in files:                                                                 
    print(f)

List folders and sub folders

You can also use os.walk() to get the folders and sub-folders.

import os
cwd =os.getcwd()
print("folder {}".format(cwd))

folders = []
for r,d,f in os.walk(cwd):
    for folder in d:
            folders.append(os.path.join(r, folder))

for f in folders:
    print(f)

You can run this both in the terminal and the web.

glob.glob()

The function .glob() can be used for the same purpose. To list all files with the py extension

import glob                                                                     
cwd = "/home/you/Desktop/"                                                    
files = [f for f in glob.glob(cwd + "**/*.py", recursive=True)]                 
for f in files:                                                                 
    print(f)

To list all folders and sub folders

import glob
cwd = "/home/you/Desktop/"
folders = [f for f in glob.glob(cwd + "**/", recursive=True)]
for f in folders:
     print(f)

If you are new to Python, I suggest this Python book and course

GUI with Python

importostar — Mon, 22 Jun 2020 16:05:49 +0000

You can build a GUI or graphical interface with Python, it's not just all terminal.

Yes, you can make desktop apps with Python. This looks like any other app on your computer like

You can see more screenshots of things you can make here

So is it hard to make GUI apps with Python?

Well, you should first know the basics of Python. It has some learning curve but it's not rocket science.

Python GUI

Basically you have to install the PyQt module and load it. Then you can create a window and add all kinds of widgets to it.

For example, the "hello world" app looks like this (source: pyqt):

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QHBoxLayout

if __name__ == '__main__':    
    app = QApplication(sys.argv)
    w = QWidget()    
    layout = QHBoxLayout()
    btn = QPushButton("Hello World!")
    layout.addWidget(btn)
    w.setLayout(layout)
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    w.show()
    sys.exit(app.exec_())

It adds a button, resizes window, sets a window title etc. PyQt has a widget for everything you can think of, so regardless of whether you want to make a web browser, an office suite or anything else you can.

If you are new to PyQt, then this is a good course

Zen of Python

importostar — Sun, 21 Jun 2020 19:58:57 +0000

Zen of Python is a set of 19 "core values" that guide the structure of the Python language for computer programs.

There's an easter egg in Python, you can use import this to load the "Zen of Python".

The core values are:

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one—and preferably only one—obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than right now.[a]
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea—let's do more of those!

As usual with the internet, things evolve. For example, this became a song and a visual studio code extension

Eitherway, this philosophy is the core of Python. You can see the proposal from 2004 PEP20

Beautiful is better than ugly
Use OR instead of ||, use AND instead of ||

Explicit is better than implicit
Code is readable by anyone

Simple is better than complex
a simple solution is always better than a complex one. So you have print("Hello") instead of sys.out.println("hello")

Flat is better than nested.
When something is not flat, it's nested. A nested loop for example is

for a in apples:
    for b in breads:
        for c in codes:

you can see this gets confusing fast, so flat is better than nested.

Readability counts
If readability didn't matter, we'd all be writing in binary code. Readability matters when it comes to programming

You can see all these zen principles are part of the Python design.

What does if name == 'main': do in Python?

importostar — Sun, 21 Jun 2020 15:15:06 +0000

What does if __name__ = '__main__' mean?

You can sometimes see this in Python script, in general this is where your Python program starts.

In many other languages, the computer program starts with a main() function. That can be the case in Python too.

main value

Let us do a quick exercise in order to grasp the specifics of the main function and the if statement.

print("module_name :{}".format(__name__))

Run the Python file and execute the file as python3 script

The outcome of the app in this example states that the variable name has a main value.

>>> print("module_name :{}".format(__name__))
module_name :__main__

So what is this main?

What does if name == "main": do?

When the above condition is tested, it must be verified whether the file is run directly by or imported by python.

The explanation demonstrates this.

    def main():
        print("module_name :{}".format(__name__))

    if __name__ == "__main__":
        main()
    else:
        print("run from import")

That's because you can import any Python script but most of the times you only want access to the functions

Like import math shouldn't execute sin, cos, pow etc automatically, you import it because you want it available.

If you are new to Python, I suggest this book

DEV Community: importostar

Which is better, Python or C++?

Which database is suitable for Python Flask?

How to build websites with Python

How to debug a Flask app?

What is Python Flask?

Learn Flask for Webdev

What is Flask?

First Apps

Advanced

import keyword with example in Python

Python import keyword

Python examples of import keyword

tkinter gui

GUI tkinter module

python list directory files

List files and folders

os.walk()

glob.glob()

GUI with Python

Python GUI

Zen of Python

What does if __name__ == '__main__': do in Python?

main value

What does if name == "main": do?

What does if name == 'main': do in Python?