w3resource

Python: Find the indices of all occurrences of target in the uneven matrix

Python Programming Puzzles: Exercise-18 with Solution

An irregular/uneven matrix, or ragged matrix, is a matrix that has a different number of elements in each row. Ragged matrices are not used in linear algebra, since standard matrix transformations cannot be performed on them, but they are useful as arrays in computing.

Write a Python program to find the indices of all occurrences of target in the uneven matrix.

Python: Find the indices of all occurrences of target in the uneven matrix.
Input:
[([1, 3, 2, 32, 19], [19, 2, 48, 19], [], [9, 35, 4], [3, 19]), 19]
Output:
[[0, 4], [1, 0], [1, 3], [4, 1]]

Input:
[([1, 2, 3, 2], [], [7, 9, 2, 1, 4]),2]
Output:
[[0, 1], [0, 3], [2, 2]]

Pictorial Presentation:

Python: Find the indices of all occurrences of target in the uneven matrix.

Sample Solution-1:

Python Code:

def test(M, T):
    return [[i, j] for i, row in enumerate(M) for j, n in enumerate(row) if n == T]
M = [[1, 3, 2, 32, 19], [19, 2, 48, 19], [], [9, 35, 4], [3, 19]]
T = 19
print("Matrix:")
print(M)
print("Target value:")
print(T)
print("Indices of all occurrences of the target value in the said uneven matrix:")
print(test(M,T))
 
M = [[1, 2, 3, 2], [], [7, 9, 2, 1, 4]]
T = 2
print("\nMatrix:")
print(M)
print("Target value:")
print(T)
print("Indices of all occurrences of the target value in the said uneven matrix:")
print(test(M,T)) 

Sample Output:

Matrix:
[[1, 3, 2, 32, 19], [19, 2, 48, 19], [], [9, 35, 4], [3, 19]]
Target value:
19
Indices of all occurrences of the target value in the said uneven matrix:
[[0, 4], [1, 0], [1, 3], [4, 1]]

Matrix:
[[1, 2, 3, 2], [], [7, 9, 2, 1, 4]]
Target value:
2
Indices of all occurrences of the target value in the said uneven matrix:
[[0, 1], [0, 3], [2, 2]]

Flowchart:

Flowchart: Python - Find a string consisting of the non-negative integers up to n inclusive.

Sample Solution-2:

Python Code:

#License: https://bit.ly/3oLErEI

def test(M, T):
    indices = []
    for i, num in enumerate(M[0]):
        if num == T:
            indices.append([0, i])
    # Search for element starting from the first column and storing the indices of the found elements in a list
    for row, row_num in zip(M[1:], range(1, len(M))):
        for i, num in enumerate(row):
            if num == T:
                indices.append([row_num, i])
    return indices

M = [[1, 3, 2, 32, 19], [19, 2, 48, 19], [], [9, 35, 4], [3, 19]]
T = 19
print("Matrix:")
print(M)
print("Target value:")
print(T)
print("Indices of all occurrences of the target value in the said uneven matrix:")
print(test(M,T))
 
M = [[1, 2, 3, 2], [], [7, 9, 2, 1, 4]]
T = 2
print("\nMatrix:")
print(M)
print("Target value:")
print(T)
print("Indices of all occurrences of the target value in the said uneven matrix:")
print(test(M,T))

Sample Output:

Matrix:
[[1, 3, 2, 32, 19], [19, 2, 48, 19], [], [9, 35, 4], [3, 19]]
Target value:
19
Indices of all occurrences of the target value in the said uneven matrix:
[[0, 4], [1, 0], [1, 3], [4, 1]]

Matrix:
[[1, 2, 3, 2], [], [7, 9, 2, 1, 4]]
Target value:
2
Indices of all occurrences of the target value in the said uneven matrix:
[[0, 1], [0, 3], [2, 2]]

Flowchart:

Flowchart: Python - Find a string consisting of the non-negative integers up to n inclusive.

Python Code Editor :

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Find a string consisting of the non-negative integers up to n inclusive.
Next: Split a string into strings if there is a space in the string, otherwise split on commas, otherwise the list of lowercase letters with odd order.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Follow us on Facebook and Twitter for latest update.