Iterate over a ‘window’ of adjacent elements in Python

Question

This is more a question of elegance and performance rather than “how to do at all”, so I\'ll just show the code:

def iterate_adjacencies(gen, fill=0, size=2,         


        

Answer 1

This page shows how to implement a sliding window with itertools. http://docs.python.org/release/2.3.5/lib/itertools-example.html

def window(seq, n=2):
    "Returns a sliding window (of width n) over data from the iterable"
    "   s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ...                   "
    it = iter(seq)
    result = tuple(islice(it, n))
    if len(result) == n:
        yield result    
    for elem in it:
        result = result[1:] + (elem,)
        yield result

Example output:

>>> list(window(range(10)))
[(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6), (6, 7), (7, 8), (8, 9)]

You'd need to change it to fill left and right if you need.