bpo-37158: Simplify and speed-up statistics.fmean() (GH-13832)

python · Jun 5, 2019 · 6c01ebc · 6c01ebc
1 parent ccf0efb
commit 6c01ebc
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Showing 2 changed files with 5 additions and 4 deletions.
diff --git a/Lib/statistics.py b/Lib/statistics.py
@@ -320,11 +320,11 @@ def fmean(data):
     except TypeError:
         # Handle iterators that do not define __len__().
         n = 0
-        def count(x):
+        def count(iterable):
             nonlocal n
-            n += 1
-            return x
-        total = fsum(map(count, data))
+            for n, x in enumerate(iterable, start=1):
+                yield x
+        total = fsum(count(data))
     else:
         total = fsum(data)
     try:

diff --git a/Misc/NEWS.d/next/Library/2019-06-04-22-25-38.bpo-37158.JKm15S.rst b/Misc/NEWS.d/next/Library/2019-06-04-22-25-38.bpo-37158.JKm15S.rst
@@ -0,0 +1 @@
+Speed-up statistics.fmean() by switching from a function to a generator.