Learning Python :-)

I've been learning python and so far so good. Here's a short list of interesting features (as I find them) - its also a helpful reference for me to remember the differences between python and C.

To Import a library

import math
import string

Comments

# whole line of comment
print stuff #remainder is comment

Loops

for char in str:
     print char

while i <= max:            print i

Conditionality

if input == type("a") and output == type('a'):
     print "input is string, output is char"

elif input == type("a") and not output == type('a'):
     print "input is string, output is NOT char"

else:
     print "unknown..."

Basic Maths

a*b  # multiplication
a**b # a to the power b
a/b  # division
a+b  # addition
a-b  # subtraction
# -------
float(a) # convert to float
int(a)   # convert to int
# -------
math.pi          # constant
math.sin(angle)  # function

strings

a = "abcdefg"
b = "hijklmn"
a+b    # abcdefghijklmn (concatination)
a**2   # abcdefgabcdefg (multiplicity)
a[1]   # b
a[0:2] # ab
a[3:]  # defg
a[:3]  # abc
# ------
string.find(haystack, needle)  # find needle in haystack
string.lowercase  # abcdefghijklmnopqrstuvwxyz
string.uppercase  # ABCDEFGHIJKLMNOPQRSTUVWXYZ
string.digits     # 0123456789
string.whitespace # contains all whitespace characters eg. \n \t %20 ...

Important:: like in C, strings cannot be altered once initialised.

Lists

myList = [10, 20, 30]
myList = ["string", 3, '4']

myList[-1]     # 20 (counts backwards)
len(myList)    # 3
del myList[1]  # [10, 30] (deletion)
myPointer = myList  # (Aliasing)
myCopy = myList[:]  # (Independent Copy)

myList = string.split("a b c d e", 'c')  # split around 'c's
                                        # myList = ["ab", "de"]
myNewList = string.Join(myList, 'c')     # joins with 'c'
                                        # myNewList = myList = "abcde"

Functions

def myFunction(myArgument)
   result = myArgument * 2
   result = result / 2
   return result

• Functions can return arrays, tuples
• ...

Keyboard IO

# Text Input
prompt = "Type Now!"
userInput = raw_input(prompt)  # text or numerical
userInput = input(prompt)      # numerical only (else error)
print "output text", outputVar # print to Terminal