About Python Lists

About Python Lists

Lists are a datatype you can use to store a collection of different pieces of information as a sequence under a single variable name

…..You can assign items to a list with

Example :

$ list_name = [item_1, item_2]

Example :

A list can also be empty:

$ empty_list = []

Example :

$ animals = ["cat", "dog", "lion", "tiger"];

 

print "The first " + animals[0]

print "The second " + animals[1]

print "The third " + animals[2]

print "The fourth " + animals[3]

Example :

$ numbers = [5, 6, 7, 8]

$ print numbers[0] + numbers[2]

$ 12

Replace list value

$ animals[2] = "zzz"

…..You can add items to the end of a list

$ number.append(“9”)

…..List Slicing

Sometimes, you only want to access a portion of a list.

number[:2]

#Grabs the first two items

number[3:]

#Grabs the fourth through last items

$ number[2:5]

# Grabs the 3 to 4 items

….List Length

$ len(number)

…......you need to search for an item in a list.

$ animals= ["ant", "bat", "cat"]

$ print animals.index("bat")

….......We can also insert items into a list.

$ animals.insert(1, "dog")

$ print animals

….If your list is a jumbled mess, you may need to sort() it.

$ animals = ["cat", "ant", "bat"]

$ animals.sort()

for animal in animals:

       print
     animal

examle 2

start_list = [5, 3, 1, 2, 4]

square_list = []

# Your code here!

for x in start_list:

           square_list.append(x**2)

square_list.sort()

print square_list