sliding window of M-by-N shape numpy.ndarray

Question

I have a numpy array of shape (6,2)

[[00,01],
 [10,11],
 [20,21],
 [30,31],
 [40,41],
 [50,51]]

I need a sliding window with step size 1 an

Answer 1

This is a pure Python implementation:

def sliding_window(arr, window=3):
    i = iter(arr)
    a = []
    for e in range(0, window): a.append(next(i))
    yield a
    for e in i:
        a = a[1:] + [e]
        yield a

An example:

# flatten array
flatten = lambda l: [item for sublist in l for item in sublist]

a = [[0,1], [10,11], [20,21], [30,31], [40,41], [50,51]]
w = sliding_window(a, width=3)
print( list(map(flatten,w)) )

[[0, 1, 10, 11, 20, 21], [10, 11, 20, 21, 30, 31], [20, 21, 30, 31, 40, 41], [30, 31, 40, 41, 50, 51]]

Benchmark

import timeit
def benchmark():
  a = [[0,1], [10,11], [20,21], [30,31], [40,41], [50,51]]
  sliding_window(a, width=3)

times = timeit.Timer(benchmark).repeat(3, number=1000)
time_taken = min(times) / 1000
print(time_taken)

1.0944640007437556e-06