# 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:**

```
# Define a function named indices_in_list that returns a list of indices where a given item (n) occurs in a list (nums_list).
def indices_in_list(nums_list, n):
# Use list comprehension to create a list of indices where the item equals n.
return [idx for idx, i in enumerate(nums_list) if i == n]
# Test the function with different lists and items, and print the results.
# Test case 1
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))
# Test case 2
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))
# Test case 3
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))
# Test case 4
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: []

**Explanation:**

Here is a breakdown of the above Python code:

- Function definition:
- The code defines a function named "indices_in_list()" that returns a list of indices where a given item (n) occurs in a list (nums_list).
- List comprehension:
- The function uses list comprehension to iterate through the elements of 'nums_list' along with their indices and creates a list of indices where the element is equal to 'n'.
- Test cases:
- The function is tested with different lists and items using print(indices_in_list(...)).

**Visual Presentation:**

**Flowchart:**

**Sample Solution-2:**

**Python Code:**

```
# Import the count function from the itertools module
from itertools import count
# Define a function named indices_in_list that returns a list of indices where a given item (n) occurs in a list (nums_list).
def indices_in_list(nums_list, n):
# Use list comprehension to create a list of indices where the item equals n, using the count() function to generate indices.
return [(i) for i, j in zip(count(), nums_list) if j == n]
# Test the function with different lists and items, and print the results.
# Test case 1
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))
# Test case 2
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))
# Test case 3
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))
# Test case 4
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: []

**Explanation: **

Here is a breakdown of the above Python code:

- Import statement:
- The code imports the count function from the itertools module.
- Function definition:
- The code defines a function named indices_in_list that returns a list of indices where a given item (n) occurs in a list (nums_list).
- List comprehension with count():
- The function uses list comprehension to iterate through the elements of nums_list along with their indices generated by count(), and creates a list of indices where the element is equal to n.
- Test cases:
- The function is tested with different lists and items using print(indices_in_list(...)).

**Flowchart:**

**Sample Solution-3:**

**Python Code:**

```
# Import the locate function from the more_itertools module
from more_itertools import locate
# Define a function named indices_in_list that returns a list of indices where a given item (n) occurs in a list (nums_list).
def indices_in_list(nums_list, n):
# Use the locate function to find all indices where the item equals n and convert it to a list.
return list(locate(nums_list, lambda x: x == n))
# Test the function with different lists and items, and print the results.
# Test case 1
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))
# Test case 2
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))
# Test case 3
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))
# Test case 4
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: []

**Explanation:**

Here is a breakdown of the above Python code:

- Import statement:
- The code imports the "locate" function from the "more_itertools()" module.
- Function definition:
- The code defines a function named "indices_in_list()" that returns a list of indices where a given item (n) occurs in a list (nums_list).
- Use of locate function:
- The "locate()" function is used to find all indices where the element equals n, and the result is converted to a list.
- Test cases:
- The function is tested with different lists and items using print(indices_in_list(...)).

**Flowchart:**

**Python Code Editor:**

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