numpy array assignment problem

Posted by Sujan on Stack Overflow See other posts from Stack Overflow or by Sujan
Published on 2010-06-17T06:33:53Z Indexed on 2010/06/17 7:13 UTC
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Hi All:

I have a strange problem in Python 2.6.5 with Numpy. I assign a numpy array, then equate a new variable to it. When I perform any operation to the new array, the original's values also change. Why is that? Please see the example below. Kindly enlighten me, as I'm fairly new to Python, and programming in general.

-Sujan

>>> import numpy as np
>>> a = np.array([[1,2],[3,4]])
>>> b = a
>>> b
array([[1, 2],
       [3, 4]])
>>> c = a
>>> c
array([[1, 2],
       [3, 4]])
>>> c[:,1] = c[:,1] + 5
>>> c

array([[1, 7],
       [3, 9]])
>>> b
array([[1, 7],
       [3, 9]])
>>> a
array([[1, 7],
       [3, 9]])

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