TypeError only integer scalar arrays can be converted to a scalar index with 1D numpy indices array

Question

I want to write a function that randomly picks elements from a training set  based on the bin probabilities provided  I divide the set indices to 11 bins  then create custom probabilities for them   bin probs    0 5  0 3  0 15  0 04  0 0025  0 0025  0 001  0 001  0 001  0 001  0 001   X train   list range 2000000    train probs   bin probs   int len X train    len bin probs     extend probabilities across bin elements train probs extend  0 001   len X train  - len train probs      a small fix to match number of elements train probs   train probs np sum train probs    normalize indices   np random choice range len X train    replace False  size 50000  p train probs  out images   X train indices astype int     this is where I get the error   I get the following error   TypeError  only integer scalar arrays can be converted to a scalar index with 1D numpy indices array   I find this weird  since I already checked the array of indices that I have created  It is 1-D  it is integer  and it is scalar   What am I missing   Note   I tried to pass indices with astype int   Same error

User · Accepted Answer

Perhaps the error message is somewhat misleading  but the gist is that X train is a list  not a numpy array  You cannot use array indexing on it  Make it an array first   out images   np array X train  indices astype int

User · Answer

A simple case that generates this error message   In  8    1 2 3 4 5  np array  1    --------------------------------------------------------------------------- TypeError                                 Traceback  most recent call last   lt ipython-input-8-55def8e1923d gt  in  lt module gt    ---- gt  1  1 2 3 4 5  np array  1     TypeError  only integer scalar arrays can be converted to a scalar index   Some variations that work   In  9    1 2 3 4 5  np array 1         this is a 0d array index Out 9   2 In  10    1 2 3 4 5  np array  1   item        Out 10   2 In  11   np array  1 2 3 4 5   np array  1    Out 11   array  2     Basic python list indexing is more restrictive than numpy s   In  12    1 2 3 4 5   1        TypeError  list indices must be integers or slices  not list   edit  Looking again at   indices   np random choice range len X train    replace False  size 50000  p train probs    indices is a 1d array of integers - but it certainly isn t scalar   It s an array of 50000 integers   List s cannot be indexed with multiple indices at once  regardless of whether they are in a list or array

User · Answer

Another case that could cause this error is  gt  gt  gt  np ndindex np random rand 60 60   TypeError  only integer scalar arrays can be converted to a scalar index  Using the actual shape will fix it   gt  gt  gt  np ndindex np random rand 60 60  shape   lt numpy ndindex object at 0x000001B887A98880 gt

User · Answer

I get this error whenever I use np concatenate the wrong way   gt  gt  gt  a   np eye 2   gt  gt  gt  np concatenate a  a  Traceback  most recent call last     File  quot  lt stdin gt  quot   line 1  in  lt module gt    File  quot  lt   array function   internals gt  quot   line 6  in concatenate TypeError  only integer scalar arrays can be converted to a scalar index  The correct way is to input the two arrays as a tuple   gt  gt  gt  np concatenate  a  a   array   1   0            0   1            1   0            0   1

[python] TypeError: only integer scalar arrays can be converted to a scalar index with 1D numpy indices array

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