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you all! I have very specific question about np.nonzero and it's function while slicing a np.array (First of all, I am not 100% sure it is called slicing). I found a Python script on the internet and get an error at the following line:

if (i in dividendsStep):
   div = dividends[1][np.nonzero(dividendsStep == (i))[0]]
   currentDividend = currentDividend + div

And I get the following error:

div = dividends[1][np.nonzero(dividendsStep == (i))[0]]
TypeError: only integer scalar arrays can be converted to a scalar index

When I drop np.nonzero(x), it doesn't generate the error but it does not generate the right answer (I know the input variables and what the answer should be).

When I print the np.nonzero part, I get the following output:

print(np.nonzero(dividendsStep==(i)))
(array([0], dtype=int32),)

When I print dividends, I get the following output

print(dividends)
[[0.2917], [2.06]]

Furthermore I think it is a python 2 script (I had to replace xrange for range). I don't know if it's relevant when I try the same code in a Python 2.7 interpreter I get the same error.

Question

What is the function of np.nonzero in the slicing? I know it returns the indices of the elements that are non-zero but it doesn't make sense in this 'slice'. If it is called different, please let me know, I will update it right away!

Answer

Ubuntu has provided the answer:

dividends=np.array(dividends)
Improve this question
4
  • What kind of object is dividends[1]? If type(dividends[1]) returns list, then see TypeError when trying to use list of integers in numpy array. Commented Jul 13, 2019 at 17:27
  • @unutbu if I print type, I get the following error: TypeError: 'str' object is not callable. When I print(dividends), I got two lists in a list. I will take a look at your suggestion. Thanks in advance! Commented Jul 13, 2019 at 17:31
  • @unutbu I also updated the question, so you can see the printout Commented Jul 13, 2019 at 17:33
  • nonzero gives a tuple of arrays. Here it is 1 array which [0] extracts. Looks like dividends is a list of lists. Lists can only be indexed with an integer, or something that can turned into one. Commented Jul 13, 2019 at 20:03
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