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pythonmultidimensional-arraymatrix-indexing

How to swap values in a 3-d array in Python?


I have a matrix (3x5) where a number is randomly selected in this matrix. I want to swap the selected number with the one down-right. I'm able to locate the index of the randomly selected number but not sure how to replace it with the one that is down then right. For example, given the matrix:

[[169 107 229 317 236]
 [202 124 114 280 106]
 [306 135 396 218 373]]

and the selected number is 280 (which is in position [1,3]), needs to be swapped with 373 on [2,4]. I'm having issues on how to move around with the index. I can hard-code it but it becomes a little more complex when the number to swap is randomly selected.

If the selected number is on [0,0], then hard-coded would look like:

selected_task = tard_generator1[0,0]
right_swap = tard_generator1[1,1]
tard_generator1[1,1] = selected_task
tard_generator1[0,0] = right_swap

Any suggestions are welcome!


Solution

  • How about something like

    chosen = (1, 2)
    right_down = chosen[0] + 1, chosen[1] + 1
    
    matrix[chosen], matrix[right_down] = matrix[right_down], matrix[chosen]
    

    will output:

    >>> a
    array([[ 0,  1,  2,  3,  4],
           [ 5,  6,  7,  8,  9],
           [10, 11, 12, 13, 14],
           [15, 16, 17, 18, 19],
           [20, 21, 22, 23, 24]])
    >>> index = (1, 2)
    >>> right_down = index[0] + 1, index[1] + 1
    >>> a[index], a[right_down] = a[right_down], a[index]
    >>> a
    array([[ 0,  1,  2,  3,  4],
           [ 5,  6, 13,  8,  9],
           [10, 11, 12,  7, 14],
           [15, 16, 17, 18, 19],
           [20, 21, 22, 23, 24]])
    

    There should be a boundary check but its omitted