python basics - Datatypes Collections and Lists

This is one of few coming series that serves as a memo of the common basic syntax when you manipulate python and focus on the basic syntax and built-in data types. 

In this post, List will be discussed, including how to define a list and how to manipulate the list and how to convert list and tuples, the major difference between list and tuple is immutability. 

in the following code , the following will be displayed.

• create a list of empty elements, one element, elements of the same type, elements of mixed types
• concat, reverse a list, remove an element from a list 

'''
Created on 2012-10-22

@author: Administrator

file: Lists.py
description: this file is to test the use of the list - one of the built-in collection types s
'''

def demoLists():
    empty_list = []
    one_elem_list = [1]
    isovalent_list = [1, 2,3,4,5,6,7, 8, 9, 12]
    unisovalent_list = [1, "two", 3, 4.0, ["a", "b"], (5,6)] # 3L is no longer supported by python 3.x
    print("*** empty list ")
    print(empty_list)
    print("*** one element list ")
    print(one_elem_list)
    print("*** isovalent list ")
    print (isovalent_list)
    print("***unisovalent list")
    print(unisovalent_list)

def list_operation():
    x = [1, 2,3, 4, 5, 6, 7, 8, 9]
    print("*** original list:")
    print(x)
    print("*** len(x): ")
    print(len(x))
    y = [-1, 0] + x
    print("** print the concatenated list:")
    print(y)
    print("**reversed list")
    x.reverse() # you cannot do x = x.reverse(), otherwise, undefined behavior will happen
    print(x)
    x.remove(1)
    print(x)
    # another way of delete one element
    del x[1]
    print(x)
    
if __name__ == '__main__':
    demoLists()
    list_operation()

the following code shows how to convert from list to tuple and vice versa.

• convert from List to tuple and the other way around. 

'''
Created on 2012-10-22

@author: Administrator
file: ListTupleOps.py
description: this file demonstrate the conversion between list and tuples
'''
def convert_and_back():
    x = [1, 2, 3, 4]
    y = tuple(x)
    print ("*** list x:")
    print(x)
    print ("*** tuple x:")
    print(y)
    x = list(y)

if __name__ == '__main__':
    convert_and_back()