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Python List index() method with Examples

Python List index() method with Examples on append(), clear(), extend(), insert(), pop(), remove(), index(), count(), pop(), reverse(), sort(), copy(), all(), bool(), enumerate(), iter(), map(), min(), max(), sum() etc.

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Python List index() Method

Python index() method returns index of the passed element. This method takes an argument and returns index of it. If the element is not present, it raises a ValueError.

If list contains duplicate elements, it returns index of first occurred element.

This method takes two more optional parameters start and end which are used to search index within a limit.

Signature

index(x[, start[, end]])

Parameters

No parameter

Return

It returns None.

Let's see some examples of index() method to understand it's functionality.

Python List index() Method Example 1

Let's first see a simple example to get index of an element using index() method.

# Python list index() Method
# Creating a list
apple = ['a','p','p','l','e']
# Method calling
index = apple.index('p')
# Displaying result
print("Index of p :",index)

Output:

Index of p : 1

Python List index() Method Example 2

The method returns index of first element occurred, if the element is duplicate. See the following example.

# Python list index() Method
# Creating a list
apple = ['a','p','p','l','e']
# Method calling
index = apple.index('l') # 3
index2 = apple.index('p') # always 1
# Displaying result
print("Index of l :",index)
print("Index of p :",index2)

Output:

Index of l : 3
Index of p : 1

Python List index() Method Example 3

The index() method throws an error ValueError if the element is not present in the list. See the example below.

# Python list index() Method
# Creating a list
apple = ['a','p','p','l','e']
# Method calling
index = apple.index('z')
# Displaying result
print("Index of l :",index)

Output:

index = apple.index('z')
ValueError: 'z' is not in list

Python List index() Method Example 4

Apart from element, the method takes two more optional parameters start and end. These are used to find index within a limit.

# Python list index() Method
# Creating a list
apple = ['a','p','p','l','e']
# Method calling
index = apple.index('p',2)	# start index
index2 = apple.index('a',0,3)	# end index
# Displaying result
print("Index of p :",index)
print("Index of a :",index2)

Output:

Index of p : 2
Index of a : 0

Next TopicPython Lists




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