Numpy array integer / float division

arrays, numpy, python

Solution

The problem with `a /= 10.0` is that it modifies the array in place, and it won't change the the dtype of the array, so all the floats are converted to integers. On the other hand `a = a / 10.0` created a new array, and the type can be changed if a new array is being created.

From docs:

Note that assignments may result in changes if assigning higher types to lower types (like floats to ints) or even exceptions (assigning complex to floats or ints):

Problem

I found the following behaviour in Python/NumPy somewhat strange: ``` In [51]: a = np.arange(10, 20) In [52]: a = a / 10.0 In [53]: a Out[53]: array([ 1. , 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9]) In [54]: a = np.arange(10, 20) In [55]: a /= 10.0 In [56]: a Out[56]: array([1, 1, 1, 1, 1, 1, 1, 1, 1, 1]) ``` I felt that `a=a/10.0` and `a/=10.0` should return the same result. Is this intended and documented somewhere?

Original source

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