only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are valid indices

Question

I am implementing fft as part of my homework. My problem lies in the implemention of shuffling data elements using bit reversal. I get the following warning:

DeprecationWarning: using a non-integer number instead of an integer will result in an error in the future.

data[x], data[y] = data[y], data[x]

And the auto grading system (provided by university) returns the following:

error: only integers, slices (:), ellipsis (...), numpy.newaxis (None) and integer or boolean arrays are valid indices.

My code is:

def shuffle_bit_reversed_order(data: np.ndarray) -> np.ndarray:
    """
    Shuffle elements of data using bit reversal of list index.

    Arguments:
    data: data to be transformed (shape=(n,), dtype='float64')

    Return:
    data: shuffled data array
    """

    # implement shuffling by reversing index bits

    size = data.size

    half = size/2;

    for x in range(size):
        xx = np.int(x)
        n = np.int(half)

        y = 0

        while n > 0:
            y += n * np.mod(xx,2)
            n /= 2
            xx = np.int(xx /2)

        if (y > x):

            data[x], data[y] = data[y], data[x]

    return data

I have already implemented the function for fft but it won't work until I get this shuffling function working. I think the problem is my data is of type 'float64' and I may have used it as an integer but I don't know how I can solve it.

What is the value of `y` when you get that error? – Barmar Jan 22 '16 at 17:40 — Barmar, Jan 22 '16 at 17:40

score 64 · Accepted Answer · answered Jan 22 '16 at 17:53

64

I believe your problem is this: in your while loop, n is divided by 2, but never cast as an integer again, so it becomes a float at some point. It is then added onto y, which is then a float too, and that gives you the warning.

answered Jan 22 '16 at 17:53

L. Hovan

656
6
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Broader picture: Indexing with a float array gives `IndexError: arrays used as indices must be of integer (or boolean) type`, indexing with a naked float or a list with floats gives the error in the title. – Jann Poppinga Jun 21 '22 at 05:50

score 38 · Answer 2 · answered May 22 '17 at 04:15

38

You can use // instead of single /. That converts to int directly.

answered May 22 '17 at 04:15

Sarvagya Gupta

861
3
13
28

6

Works like a charm – Val Berthe Mar 28 '18 at 09:08
1

That was the ticket! – JayJay123 Dec 07 '19 at 20:51

score 3 · Answer 3 · edited Nov 13 '19 at 10:53

3

put a int infront of the all the voxelCoord's...Like this below :

patch = numpyImage [int(voxelCoord[0]),int(voxelCoord[1])- int(voxelWidth/2):int(voxelCoord[1])+int(voxelWidth/2),int(voxelCoord[2])-int(voxelWidth/2):int(voxelCoord[2])+int(voxelWidth/2)]

edited Nov 13 '19 at 10:53

David Buck

3,752
35
31
35

answered Nov 13 '19 at 10:14

Vijay Meduri

31
2

only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are valid indices

3 Answers3

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