diff --git a/Lib/lib-old/whrandom.py b/Lib/lib-old/whrandom.py new file mode 100644 index 00000000000..bc0d1a4520e --- /dev/null +++ b/Lib/lib-old/whrandom.py @@ -0,0 +1,144 @@ +"""Wichman-Hill random number generator. + +Wichmann, B. A. & Hill, I. D. (1982) +Algorithm AS 183: +An efficient and portable pseudo-random number generator +Applied Statistics 31 (1982) 188-190 + +see also: + Correction to Algorithm AS 183 + Applied Statistics 33 (1984) 123 + + McLeod, A. I. (1985) + A remark on Algorithm AS 183 + Applied Statistics 34 (1985),198-200 + + +USE: +whrandom.random() yields double precision random numbers + uniformly distributed between 0 and 1. + +whrandom.seed(x, y, z) must be called before whrandom.random() + to seed the generator + +There is also an interface to create multiple independent +random generators, and to choose from other ranges. + + + +Multi-threading note: the random number generator used here is not +thread-safe; it is possible that nearly simultaneous calls in +different theads return the same random value. To avoid this, you +have to use a lock around all calls. (I didn't want to slow this +down in the serial case by using a lock here.) +""" + +import warnings +warnings.warn("the whrandom module is deprecated; please use the random module", + DeprecationWarning) + +# Translated by Guido van Rossum from C source provided by +# Adrian Baddeley. + + +class whrandom: + def __init__(self, x = 0, y = 0, z = 0): + """Initialize an instance. + Without arguments, initialize from current time. + With arguments (x, y, z), initialize from them.""" + self.seed(x, y, z) + + def seed(self, x = 0, y = 0, z = 0): + """Set the seed from (x, y, z). + These must be integers in the range [0, 256).""" + if not type(x) == type(y) == type(z) == type(0): + raise TypeError, 'seeds must be integers' + if not (0 <= x < 256 and 0 <= y < 256 and 0 <= z < 256): + raise ValueError, 'seeds must be in range(0, 256)' + if 0 == x == y == z: + # Initialize from current time + import time + t = long(time.time() * 256) + t = int((t&0xffffff) ^ (t>>24)) + t, x = divmod(t, 256) + t, y = divmod(t, 256) + t, z = divmod(t, 256) + # Zero is a poor seed, so substitute 1 + self._seed = (x or 1, y or 1, z or 1) + + def random(self): + """Get the next random number in the range [0.0, 1.0).""" + # This part is thread-unsafe: + # BEGIN CRITICAL SECTION + x, y, z = self._seed + # + x = (171 * x) % 30269 + y = (172 * y) % 30307 + z = (170 * z) % 30323 + # + self._seed = x, y, z + # END CRITICAL SECTION + # + return (x/30269.0 + y/30307.0 + z/30323.0) % 1.0 + + def uniform(self, a, b): + """Get a random number in the range [a, b).""" + return a + (b-a) * self.random() + + def randint(self, a, b): + """Get a random integer in the range [a, b] including + both end points. + + (Deprecated; use randrange below.)""" + return self.randrange(a, b+1) + + def choice(self, seq): + """Choose a random element from a non-empty sequence.""" + return seq[int(self.random() * len(seq))] + + def randrange(self, start, stop=None, step=1, int=int, default=None): + """Choose a random item from range(start, stop[, step]). + + This fixes the problem with randint() which includes the + endpoint; in Python this is usually not what you want. + Do not supply the 'int' and 'default' arguments.""" + # This code is a bit messy to make it fast for the + # common case while still doing adequate error checking + istart = int(start) + if istart != start: + raise ValueError, "non-integer arg 1 for randrange()" + if stop is default: + if istart > 0: + return int(self.random() * istart) + raise ValueError, "empty range for randrange()" + istop = int(stop) + if istop != stop: + raise ValueError, "non-integer stop for randrange()" + if step == 1: + if istart < istop: + return istart + int(self.random() * + (istop - istart)) + raise ValueError, "empty range for randrange()" + istep = int(step) + if istep != step: + raise ValueError, "non-integer step for randrange()" + if istep > 0: + n = (istop - istart + istep - 1) / istep + elif istep < 0: + n = (istop - istart + istep + 1) / istep + else: + raise ValueError, "zero step for randrange()" + + if n <= 0: + raise ValueError, "empty range for randrange()" + return istart + istep*int(self.random() * n) + + +# Initialize from the current time +_inst = whrandom() +seed = _inst.seed +random = _inst.random +uniform = _inst.uniform +randint = _inst.randint +choice = _inst.choice +randrange = _inst.randrange