How to strip a 2d array in python Numpy Array?

Question

Suppose i have an np array like this-

[[ 0  1  2  3  4]
 [ 5  6  7  8  9]
 [10 11 12 13 14]
 [15 16 17 18 19]]

I want a function fun_strip(x) . After applying this function i want the returned array to look like this:

[[ 6  7  8]
 [11 12 13]]

it it nott clear by wich principle you want to select the elments of thee new array, can you please explain — Indiano, Dec 01 '22 at 14:48
`def strip(arr): return np.array([[6,7,8],[11,12,13]])`. Unless you wish to specify another constraint. Definition of what you want by a sole example may lead to perfectly correct answer that don't fit your real need. Like mine. — chrslg, Dec 01 '22 at 15:32

score 1 · Answer 1 · answered Dec 01 '22 at 14:52

1

Do you want to remove 1 value on each border?

a = np.array([[ 0,  1,  2,  3,  4],
              [ 5,  6,  7,  8,  9],
              [10, 11, 12, 13, 14],
              [15, 16, 17, 18, 19]])

out = a[1:a.shape[0]-1, 1:a.shape[1]-1]

Generalization for N:

N = 1
a[N:a.shape[0]-N, N:a.shape[1]-N]

Output:

array([[ 6,  7,  8],
       [11, 12, 13]])

answered Dec 01 '22 at 14:52

mozway

194,879
13
39
75

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Is there a reason not to use a simpler `a[1:-1, 1:-1]`? – dm2 Dec 01 '22 at 14:57
Thanks this is the solve i was trying to figure out. – WsTec Dec 01 '22 at 15:33
1

@dm2 in case N=0, but for N>0 you're right it's more simple – mozway Dec 01 '22 at 16:26

score 0 · Answer 2 · answered Dec 01 '22 at 14:54

Your specific example:

arr = np.array([[0,  1,  2,  3,  4],
                [5,  6,  7,  8,  9],
                [10, 11, 12, 13, 14],
                [15, 16, 17, 18, 19]])
arr[1:3, 1:4]

Strip function in general:

def strip_func(arr, r1, r2, c1, c2):
   return(arr[r1:r2+1, c1:c2+1])

r1 and r2 is the beginning and end of the range of rows that you want to subset. c1 and c2 is the same but for the columns.

Indiano · Answer 3 · 2023-05-12T13:07:09.343

0

A solution that works only for the specified use case would be:

def fun_strip(array):
    return np.array([array[1][1:4],array[2][1:4]])

You need to specify better what the use case is if you want a better, general implementation

edited May 12 '23 at 13:07

answered Dec 01 '22 at 14:59

Indiano

684
5
19

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@ShahidaYeasmin you may want to edit your question to say that, then. As is, you haven't said at all what is the task. – chrslg Dec 01 '22 at 15:33
Sincerely apologize to give less information in my questions. and thanks for your support. – WsTec Dec 01 '22 at 15:41

How to strip a 2d array in python Numpy Array?

3 Answers3