A simple note for python programming

Nutshell

Install:

$ sudo apt-get install python-pip -y

Check location of a package

$ sudo pip3 show <package_name>

To set a python version as default:

• To check the current python version:

Python 2.* $ python --version

Python 3 $ python3 --version

The simple safe way is use alias. Add into your ~/.bashrc or ~/.bash_aliases

alias python=python3

Print

String

a = "Bubu"
b = "is a fat pet"
c = a + " " + b # output: "bubu is a fat pet"

• Convert a type to string using str() function

  a = tem
  b = 1
  c = a + b #Error
  c = a + str(b) # c = "tem1"
  

  Array

• Array in Python is implement as a list data structure
• Elements in an array could be in various type

  a = [1, 2.3, "girl", 2+0j]
  

• Two lists could be concat using +
• len(array): return length of the array

Loop

A common loop syntax in C/C++ is:

for (i = 0; i < n; i++){
  loop body
}

In Python, the loop becomes:

for i in range(0, n):
<tab> loop body

Note the colon : is required at the end of the loop statement

A better alternative (although longer) way is using while loop. It’s better because you can easily control the iterator variable with while loop.

count = 0
while True:
  print(count)
  count += 1
  if count >= 10:
    break