Introduction to Python

Learning Python with virtual environment

[sudo] pip install virtualenv
source bin/activate
deactivate

Read Documentations Here Check my script collections Here

Python Basics

$python-math-operator$ python-common-datatype python-variable-names

String concatenation

>>> 'Alice' + 'Bob'
'AliceBob'

>>> 'Alice' + 42 #Error

>>> 'Alice' * 5
'AliceAliceAliceAliceAlice'

>>> 'Alice' * 'Bob' #Error

>>> 'Alice' * 5.0 #Error

Common functions

print('what is your name?') # This is comment

myName = input()

print('It is good to meet you, ' + myName)

print('The length of your name is: ')
print(len(myName))

str()
int()
float()

Flow control

Boolean values

comparison-operators

Boolean Operators

boolean-and-operator

boolean-or-operator

boolean-not-operator

If Statement

if name === 'Alice':
  print('Hi, Alice')
elif age < 12:
  print('You are not Alice, kiddo.')
else:
  print('Hello, stranger.')

Loops

spam = 0
while spam < 5:
  print('hello.')
  spam = spam + 1 # break, continue, applies

for i in range(5) # range([start], end, [step])
  print('Count (' + i + ')')

Functions

def hello():
  print('Howdy!')

hello() # Function call

def hello(name):
  print('Hello ' + name)

hello('Bob') # Function call with arguments

The None Value

>>> spam = print('Hello!')
Hello!
>>> None == spam
True

Keyword Arguments and print()

print('Hello')
print('World')
# output:
# Hello
# World

print('Hello', end='')
print('World')
# output:
# HelloWorld

>>> print('cats', 'dogs', 'mice')
cats dogs mice

>>> print('cats', 'dogs', 'mice', sep=',')
cats,dogs,mice

Local and Global scopes applies

def spam():
  global eggs # global keyword to make changes in local scopes
  eggs = 'spam'
def bacon():
  eggs = 'bacon' # this is local var

eggs = 'global'  
spam()
print(eggs)

Exception

def spam(divideBy):
  try:
    return 42/divideBy
  except ZeroDivisionError:
    print('Error: Invalid argument.')

Written on July 20, 2017