Slice border of 2D NumPy array by integer value

问题

I would like to slice a 2D NumPy array by an integer value, but I cannot find a way to do this properly. I need to slice the "border" of the matrix by a certain number of rows/columns.

Say the array is:

a = np.reshape(np.arange(25),(5,5))
print a

[[ 0  1  2  3  4]
 [ 5  6  7  8  9]
 [10 11 12 13 14]
 [15 16 17 18 19]
 [20 21 22 23 24]]

slice_val = 1

b = a[:-slice_val,:-slice_val]
print "\n", b

What I get is:

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

, but I want something like this:

[[6  7  8 ]
 [11 12 13]
 [16 17 18]]

回答1:

Use

b = a[slice_val:-slice_val, slice_val:-slice_val]

to slice the borders by slice_val.

回答2:

arr=np.ones(25).reshape(5,5)
arr
slice_of_array=arr[1:4,1:4]
slice_of_array

来源：https://stackoverflow.com/questions/36411483/slice-border-of-2d-numpy-array-by-integer-value