python - Numpy, grouping every N continuous element? -

i extract groups of every n continuous elements array. numpy array this:

a = numpy.array([1,2,3,4,5,6,7,8]) 

i wish have (n=5):

array([[1,2,3,4,5],        [2,3,4,5,6],        [3,4,5,6,7],        [4,5,6,7,8]]) 

so can run further functions such average , sum. how produce such array?

you use rolling_window blog

def rolling_window(a, window):     shape = a.shape[:-1] + (a.shape[-1] - window + 1, window)     strides = a.strides + (a.strides[-1],)     return np.lib.stride_tricks.as_strided(a, shape=shape, strides=strides)  in [37]: = np.array([1,2,3,4,5,6,7,8])  in [38]: rolling_window(a, 5) out[38]: array([[1, 2, 3, 4, 5],        [2, 3, 4, 5, 6],        [3, 4, 5, 6, 7],        [4, 5, 6, 7, 8]]) 

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i liked @divkar's solution. however, larger arrays , windows, may want use rolling_window?

in [55]: = np.arange(1000)  in [56]: %timeit rolling_window(a, 5) 100000 loops, best of 3: 9.02 µs per loop  in [57]: %timeit broadcast_f(a, 5) 10000 loops, best of 3: 87.7 µs per loop  in [58]: %timeit rolling_window(a, 100) 100000 loops, best of 3: 8.93 µs per loop  in [59]: %timeit broadcast_f(a, 100) 1000 loops, best of 3: 1.04 ms per loop