user2046488 user2046488 - 11 days ago 7
Python Question

Python, numpy sort array

I'am using numpy and have an array (ndarray type) which contain some values. Shape of this array 1000x1500. I reshaped it

brr = np.reshape(arr, arr.shape[0]*arr.shape[1])


when I trying

brr.reverse()
AttributeError: ‘numpy.ndarray’ object has no attribute ‘reverse’


get error.
How I can sort this array ?

Answer

If you just want to reverse it:

brr[:] = brr[::-1]

Actually, this reverses along axis 0. You could also revert on any other axis, if the array has more than one.

To sort in reverse order:

>>> arr = np.random.random((1000,1500))
>>> brr = np.reshape(arr, arr.shape[0]*arr.shape[1])
>>> brr.sort()
>>> brr = brr[::-1]
>>> brr
array([  9.99999960e-01,   9.99998167e-01,   9.99998114e-01, ...,
     3.79672182e-07,   3.23871190e-07,   8.34517810e-08])

or, using argsort:

>>> arr = np.random.random((1000,1500))
>>> brr = np.reshape(arr, arr.shape[0]*arr.shape[1])
>>> sort_indices = np.argsort(brr)[::-1]
>>> brr[:] = brr[sort_indices]
>>> brr
array([  9.99999849e-01,   9.99998950e-01,   9.99998762e-01, ...,
         1.16993050e-06,   1.68760770e-07,   6.58422260e-08])