Python Notes - Libraries

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Python has thousands of libary functions pre-written for you to use. They a grouped into modules, which can be imported. We specify the module name when we use the function or constant, as in

import math    # math gets you sin, cos
y = math.sin(0.6)
x = math.cos(0.4)
print math.pi   # prints 3.1415...etc...
You will need to do a search of the python documentation to see the full range of modules. Use your Python system, or: http://docs.python.org/modindex.html

Here we will provide a short list of the more common functions used in intro programs.

Built-in functions

These need not be imported. Look at the Lists page for details of

len  max  min  range len  
We also have:

f = float("12.34")    # converts string to  a decimal (float) number
f = float(12)         # changes int (whole number) into  a decimal (i.e 12.0)
x = pow(a, b)         # a to the power b
x = round(y)          # rounds to nearest integer (0.5 goes to number above)
s = str(n)            # converts n into  a string



Libraries

The string library has useful stuff for case conversion, searching, splitting strings into separate items, etc

The random library:

import random
x = random.randint(0,3)  # random integer in range 0 to 3 inclusive
x = random.choice( ["up", "down", "left", "right"] )  # random choice from list,
                                                      #   tuple, or string

Contents   Installing Python   Variables   Input/Output   if   while   Functions - def   Scopes (local/global)   Function parameters   Lists (arrays)   Dictionaries   Tuples   Files   Libraries   Hints, tips