Lists in Python

Skill - Lists in Python

Table of Contents

Skills Required

• Setup python development environment
• Basic Printing in Python
• Commenting in Python
• Managing Variables in python

Please make sure to have all the skills mentioned above to understand and execute the code mentioned below. Go through the above skills if necessary for reference or revision

Lists means just a list of objects

Main Code

Basic stuff

# creating a list and storing in variable x
x = [0,2,4,5,9]

# print the first element (index=0)
print(x[0])
# print the third element (index=2)
print(x[2])

# print length of the list using len function
print(len(x))

“append” function to add new elements at the end

# create a list
x = [1,5,3,7,4]

# add 10 at the end of the list
x.append(10)
# add 15 at the end of the list
x.append(15)

# print to verify that 10, 15 are added at the end
print(x)
# this prints [1,5,3,7,4,10,15]

“extend” function to add multiple new elements at the end

# create a list
x = [1,5,3,7,4]

# add numbers 10, 15 at the end of the list
x.extend([10, 15])

# print to verify that 10, 15 are added at the end
print(x)
# this prints [1,5,3,7,4,10,15]

“insert” function to add new element at any position

# create a list
x = [1,5,3,7,4]

# add number 54 at the start the list
x.insert(0, 54)

# add number 21 at the second last position of the list
x.insert(len(x)-1, 21)

# print to verify that 54, 21 are added at the correct positions
print(x)
# this prints [54, 1, 5, 3, 7, 21, 4]

“index” function to search for the first occurrence in the list

# initialize a list
x = ['a','b','c','b', 'a']

# find the position of 'b'
print(x.index('b'))
# prints 1

# find the position of 'b', but search from index 2
print(x.index('b', 2))
# prints 3

“sorted” function to sort a list

x = [5,1,2,9,4,6]
x = sorted(x)
print(x)
# prints [1, 2, 4, 5, 6, 9]

# sort in descending order using reverse=True input
x = sorted(x, reverse=True)
print(x)
# prints [9, 6, 5, 4, 2, 1]

x = ['z','w','p','a']
x = sorted(x)
print(x)
# prints ['a', 'p', 'w', 'z']

“reverse” function

x = [4,6,3,7,9]
x.reverse()
print(x)
# prints [9, 7, 3, 6, 4]

slicing a list using : operator

x = [0, 1, 2, 3, 4, 5]

# get elements from index 2 till end
print(x[2:])
# prints [2, 3, 4, 5]

# get elements from start till index 1
print(x[:2])
# prints [0, 1]

# get elements from index 2 but leave last one element
print(x[2:-1])
# prints [2, 3, 4]

Video

Video for this post can be found here

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Online Interpreter

You can run these codes online at https://www.programiz.com/python-programming/online-compiler/

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