[Python-checkins] r46841 - python/branches/release24-maint/Lib/random.py
tim.peters
python-checkins at python.org
Sun Jun 11 00:54:19 CEST 2006
Author: tim.peters
Date: Sun Jun 11 00:54:19 2006
New Revision: 46841
Modified:
python/branches/release24-maint/Lib/random.py
Log:
Merge rev 46840 from trunk.
shuffle() doscstring: Removed warning about sequence length
versus generator period. While this was a real weakness of the
older WH generator for lists with just a few dozen elements,
and so could potentially bite the naive ;-), the Twister should
show excellent behavior up to at least 600 elements.
Modified: python/branches/release24-maint/Lib/random.py
==============================================================================
--- python/branches/release24-maint/Lib/random.py (original)
+++ python/branches/release24-maint/Lib/random.py Sun Jun 11 00:54:19 2006
@@ -29,13 +29,12 @@
General notes on the underlying Mersenne Twister core generator:
* The period is 2**19937-1.
-* It is one of the most extensively tested generators in existence
-* Without a direct way to compute N steps forward, the
- semantics of jumpahead(n) are weakened to simply jump
- to another distant state and rely on the large period
- to avoid overlapping sequences.
-* The random() method is implemented in C, executes in
- a single Python step, and is, therefore, threadsafe.
+* It is one of the most extensively tested generators in existence.
+* Without a direct way to compute N steps forward, the semantics of
+ jumpahead(n) are weakened to simply jump to another distant state and rely
+ on the large period to avoid overlapping sequences.
+* The random() method is implemented in C, executes in a single Python step,
+ and is, therefore, threadsafe.
"""
@@ -253,11 +252,6 @@
Optional arg random is a 0-argument function returning a random
float in [0.0, 1.0); by default, the standard random.random.
-
- Note that for even rather small len(x), the total number of
- permutations of x is larger than the period of most random number
- generators; this implies that "most" permutations of a long
- sequence can never be generated.
"""
if random is None:
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