Python numpy convert 2d array in 1d array sorted

Question

I have a 2D numpy array and I want to change this array into a 1D which is sorted. For example:

A = [[1,0,2],
     [0,3,0]]

I want this to be like:

B = [3,2,1,0,0,0]

Any idea how I can do this using python modules and not to write a sorting algorithm or anything like that ?

Thanks

Divakar · Accepted Answer · 2015-04-17 22:31:00Z

4

Assuming you are looking to sort them in descending order -

In [127]: A
Out[127]: [[1, 0, 2], [0, 3, 0]]

In [128]: B = np.sort(np.array(A).ravel())

In [129]: B[::-1]
Out[129]: array([3, 2, 1, 0, 0, 0])

Basically, it involves three steps: Flatten the array with ravel(), sort it with np.sort and then reverse the indexing for an effect of descending order sorting.

edited Apr 17, 2015 at 22:31

answered Apr 17, 2015 at 22:11

Divakar

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2 Comments

Divakar Over a year ago

@EdChum haha happens I guess! :)

Divakar Over a year ago

@EdChum Ah that was okay! Well, I liked your one-liner though.

xsami · Accepted Answer · 2015-04-17 22:17:54Z

1

This is my solution:

A = [[1,0,2], [0,3,0]]
B = []
for i in range(len(A)):
    for j in range(len(A[i])):
        B.append(A[i][j])

B.sort(cmp=None, key=None, reverse=True)
print B

You can see my code running here: http://ideone.com/P8xBPK

answered Apr 17, 2015 at 22:17

xsami

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