Python - Access List Items

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In Python, a list is a sequence. Each object in the list is accessible with its index. The index starts from 0. Index or the last item in the list is "length-1". To access the values in a list, use the square brackets for slicing along with the index or indices to obtain value available at that index.

The slice operator fetches one or more items from the list. Put index on square brackets to retrieve item at its position.

obj = list1[i]

Example 1

Take a look at the following example −

list1 = ["Rohan", "Physics", 21, 69.75]
list2 = [1, 2, 3, 4, 5]

print ("Item at 0th index in list1: ", list1[0])
print ("Item at index 2 in list2: ", list2[2])

It will produce the following output −

Item at 0th index in list1: Rohan
Item at index 2 in list2: 3

Python allows negative index to be used with any sequence type. The "-1" index refers to the last item in the list.

Example 2

Let's take another example −

list1 = ["a", "b", "c", "d"]
list2 = [25.50, True, -55, 1+2j]

print ("Item at 0th index in list1: ", list1[-1])
print ("Item at index 2 in list2: ", list2[-3])

It will produce the following output −

Item at 0th index in list1: d
Item at index 2 in list2: True

The slice operator extracts a sublist from the original list.

Sublist = list1[i:j]

Parameters

• i − index of the first item in the sublist

• j − index of the item next to the last in the sublist

This will return a slice from i^th to (j-1)^th items from the list1.

Example 3

While slicing, both operands "i" and "j" are optional. If not used, "i" is 0 and "j" is the last item in the list. Negative index can be used in slicing. Take a look at the following example −

list1 = ["a", "b", "c", "d"]
list2 = [25.50, True, -55, 1+2j]

print ("Items from index 1 to 2 in list1: ", list1[1:3])
print ("Items from index 0 to 1 in list2: ", list2[0:2])

It will produce the following output −

Items from index 1 to 2 in list1: ['b', 'c']
Items from index 0 to 1 in list2: [25.5, True]

Example 4

list1 = ["a", "b", "c", "d"]
list2 = [25.50, True, -55, 1+2j]
list4 = ["Rohan", "Physics", 21, 69.75]
list3 = [1, 2, 3, 4, 5]

print ("Items from index 1 to last in list1: ", list1[1:])
print ("Items from index 0 to 1 in list2: ", list2[:2])
print ("Items from index 2 to last in list3", list3[2:-1])
print ("Items from index 0 to index last in list4", list4[:])

It will produce the following output −

Items from index 1 to last in list1: ['b', 'c', 'd']
Items from index 0 to 1 in list2: [25.5, True]
Items from index 2 to last in list3 [3, 4]
Items from index 0 to index last in list4 ['Rohan', 'Physics', 21, 69.75]