Lists and Sorting in Python

Video Explanation by Prateek Narang

Difficulty:

Easy

Concepts Used:

Basics

Solution

# Create a list

l1 = []
print type(l1)

l2 = [1,2,3]
print l2
# Acesss the ith element using l[i]
print l2[1]

l3 = [1,2,5,"Hello"]
l4 = l2 + l3
print l4

# We can the list contructor list is inbuilt class

mylist = list()
mylist.append("apple")
mylist.append("guava")
print len(mylist)
print mylist

# Sorting on lists
numbers = [1,2,4,3,5,6]

# sorted function returns a new list which gets printed, doesnt change the actual list
numbers2 = sorted(numbers)

print numbers2
print numbers

# sort function 
numbers.sort()

print "After sorting numbers", numbers



<type 'list'>
[1, 2, 3]
2
[1, 2, 3, 1, 2, 5, 'Hello']
2
['apple', 'guava']
[6, 5, 4, 3, 2, 1]
[1, 2, 4, 3, 5, 6]
After sorting numbers [1, 2, 3, 4, 5, 6]

# Sorting on lists
numbers = [1,2,4,3,5,6]

print sorted(numbers,reverse=True)

# Nested lists 
a = [ 1,2,3,["Four",5,6],[2,3,4]]
print a
print type(a[3][0])   #behaves like a 2-d array

# Concatenations
b = [1,29.0]

print a + b 

b = b*3
print b

# Splicing

numbers = ["zero","one","two","three","four"]

print numbers[1:3]
print numbers[ : ]




[6, 5, 4, 3, 2, 1]
[1, 2, 3, ['Four', 5, 6], [2, 3, 4]]
<type 'str'>
[1, 2, 3, ['Four', 5, 6], [2, 3, 4], 1, 29.0]
[1, 29.0, 1, 29.0, 1, 29.0]
['one', 'two']
['zero', 'one', 'two', 'three', 'four']