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python - Confusion in size of a numpy array

Python numpy array 'size' confuses me a lot

a = np.array([1,2,3])
a.size = (3, )
------------------------
b = np.array([[2,1,3,5],
             [2,2,5,1],
             [3,6,99,5]])
b.size = (3,4)

'b' makes sense since it has 3 rows and 4 columns in each But how is 'a' size = (3, ) ? Shouldn't it be (1,3) since its 1 row and 3 columns?

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No, a numpy.ndarray with shape (1, 3) would look like:

np.array([[1,2,3]])

Think about how the shape corresponds to indexing:

arr[0, ...]  #First row

I still have three more options, namely:

arr[0,0]
arr[0,1]
arr[0,2]

Try doing that with a 1 dimensional array


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