Basic Python

WIP (Work in Progress) In this post, I will share some of the Python programming

The Zen of Python

by Tim Peters

import this

• 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.
• 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!

__main__

__init__

decorators

Decorators is a function where we want to decorate a function without changing the original function

def dev(a,b):
    return a/b

dev(2,4)

Result

0.5

Let say we want to execute above function and want to alter the function or add another into the original function, we use decorator

def smart_dev(func):
    def inner_function(a,b):
        if a<b:
            a,b = b,a
        return func(a,b)
    return inner_function

@smart_dev
def dev(a,b):
    return a/b

dev(2,4)

Result

2

https://www.youtube.com/watch?v=FsAPt_9Bf3U

Class and object

Why Class in Python?

To group the data and function for easy to use and build upon

Object is the subset of the class. The object is created by the defined object Class Example:

class Class_Name:
  def __init__(self, att_1, att_2, att_3):
    self.att_1 = att_1
    self.att_2 = att_2
    self.att_3 = att_3

  def function_class(self):
    print(self.att_1)

Method

Method is the function associated with the class Add self to each of the method of the class Class_Name

def function_class(self):

Constructor

The custome constructor like example below is how to define the attributes in more efficient way

def __init__(self, att_1, att_2, att_3):

Therefore to run the example of the Class above

variable1 = Class_Name(att_1, att_2, att_3)

String formatting

There are multiple ways on how you can do string-formatting Let say we have an output like this

My name is Ahmad and I am 20 years old.

Example

person = {'name': 'Ahmad', 'age': 20}
sentence = 'My name is ' + person['name'] + ' and I am ' + str(person['age']) + ' years old.'

On the example above, you need to convert the integer to string due to error TypeError: can only concatenate str (not "int") to str

You could refer to the date time format based on official documentation of Python datetime library

import datetime
my_date = datetime.datetime(2016, 9, 24, 12, 30, 45)
sentence = '{0:%B %d, %Y} fell on a {2:%d} and was the {1:%y} day of the year'.format(my_date, my_date, my_date)

On the example above you can either add 0 at the beginning of the :%B %d, %Y or you put the 3 placeholders but provide only a value to the format. Therefore you can either put 3 values in the format or assign only one value to the format and add 0:.

str() and repr()

str should be readable repr should be unambigious

Namedtuple

To increase the readability of the tuple

from collections import namedtuple

argparse

Argparse is used to parse python scripts parameters

import argparse

if __name__ = '__main__':
  # Initialize parser
  parser = argparse.ArgumentParser()
  parser.add_argument('')
  # Add the additional parameter and add the parser
  args = parser.parse_args()