From: Raymond Hettinger Date: Wed, 30 Dec 2020 20:51:19 +0000 (-0800) Subject: Minor improvements to the convolve() recipe (GH-24012) X-Git-Tag: v3.10.0a4~36 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f421bfce80730cb0ff5cbe14727ac30cf0462eed;p=thirdparty%2FPython%2Fcpython.git Minor improvements to the convolve() recipe (GH-24012) * Minor improvement to speed and space efficiency for the convolve() recipe * Don't require convolve's kernel to be a sequence. --- diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 03416a0a7fbc..fd77f99a88f5 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -791,9 +791,9 @@ which incur interpreter overhead. # convolve(data, [0.25, 0.25, 0.25, 0.25]) --> Moving average (blur) # convolve(data, [1, -1]) --> 1st finite difference (1st derivative) # convolve(data, [1, -2, 1]) --> 2nd finite difference (2nd derivative) - kernel = list(reversed(kernel)) + kernel = tuple(kernel)[::-1] n = len(kernel) - window = collections.deque([0] * n, maxlen=n) + window = collections.deque([0], maxlen=n) * n for x in chain(signal, repeat(0, n-1)): window.append(x) yield sum(map(operator.mul, kernel, window))