﻿ Python: Find the indices of all occurrences of a given item in a given list - w3resource

# Python: Find the indices of all occurrences of a given item in a given list

## Python Basic - 1: Exercise-109 with Solution

Write a Python program to find the indices of all occurrences of a given item in a given list.

Sample Solution-1:

Python Code:

``````def indices_in_list(nums_list, n):
return [idx for idx, i in enumerate(nums_list) if i == n]
nums = [1,2,3,4,5,2]
print("Original list of numbers:",nums)
n = 2
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [3,1,2,3,4,5,6,3,3]
print("\nOriginal list of numbers:",nums)
n = 3
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,-4,5,2,-4]
print("\nOriginal list of numbers:",nums)
n = -4
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,4,5,2]
print("\nOriginal list of numbers:",nums)
n = 7
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
``````

Sample Output:

```Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 2
Indices of all occurrences of the said item in the given list:
[1, 5]

Original list of numbers: [3, 1, 2, 3, 4, 5, 6, 3, 3]
Given Number 3
Indices of all occurrences of the said item in the given list:
[0, 3, 7, 8]

Original list of numbers: [1, 2, 3, -4, 5, 2, -4]
Given Number -4
Indices of all occurrences of the said item in the given list:
[3, 6]

Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 7
Indices of all occurrences of the said item in the given list:
[]
```

Pictorial Presentation:  Flowchart: Sample Solution-2:

Python Code:

``````from itertools import count
def indices_in_list(nums_list, n):
return [(i) for i, j in zip(count(), nums_list) if j == n]
nums = [1,2,3,4,5,2]
print("Original list of numbers:",nums)
n = 2
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [3,1,2,3,4,5,6,3,3]
print("\nOriginal list of numbers:",nums)
n = 3
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,-4,5,2,-4]
print("\nOriginal list of numbers:",nums)
n = -4
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,4,5,2]
print("\nOriginal list of numbers:",nums)
n = 7
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
``````

Sample Output:

```Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 2
Indices of all occurrences of the said item in the given list:
[1, 5]

Original list of numbers: [3, 1, 2, 3, 4, 5, 6, 3, 3]
Given Number 3
Indices of all occurrences of the said item in the given list:
[0, 3, 7, 8]

Original list of numbers: [1, 2, 3, -4, 5, 2, -4]
Given Number -4
Indices of all occurrences of the said item in the given list:
[3, 6]

Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 7
Indices of all occurrences of the said item in the given list:
[]
```

Flowchart: Sample Solution-3:

Python Code:

``````from more_itertools import locate
def indices_in_list(nums_list, n):
return list(locate(nums_list, lambda x: x == n))
nums = [1,2,3,4,5,2]
print("Original list of numbers:",nums)
n = 2
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [3,1,2,3,4,5,6,3,3]
print("\nOriginal list of numbers:",nums)
n = 3
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,-4,5,2,-4]
print("\nOriginal list of numbers:",nums)
n = -4
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
nums = [1,2,3,4,5,2]
print("\nOriginal list of numbers:",nums)
n = 7
print("Given Number",n)
print("Indices of all occurrences of the said item in the given list:")
print(indices_in_list(nums, n))
``````

Sample Output:

```Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 2
Indices of all occurrences of the said item in the given list:
[1, 5]
Original list of numbers: [3, 1, 2, 3, 4, 5, 6, 3, 3]
Given Number 3
Indices of all occurrences of the said item in the given list:
[0, 3, 7, 8]
Original list of numbers: [1, 2, 3, -4, 5, 2, -4]
Given Number -4
Indices of all occurrences of the said item in the given list:
[3, 6]
Original list of numbers: [1, 2, 3, 4, 5, 2]
Given Number 7
Indices of all occurrences of the said item in the given list:
[]
```

Flowchart: Python Code Editor:

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