Mailman 3 August 2009 - Python-Dev

[RELEASED] Python 3.1.1
by Benjamin Peterson Aug. 17, 2009

Aug. 17, 2009

On behalf of the Python development team, I'm happy to announce the first bugfix release of the Python 3.1 series, Python 3.1.1. This bug fix release fixes many normal bugs and several critical ones including potential data corruption in the io library. Python 3.1 focuses on the stabilization and optimization of the features and changes that Python 3.0 introduced. For example, the new I/O system has been rewritten in C for speed. File system APIs that use unicode strings now handle paths … [View More]

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Re: [Python-Dev] random number generator state
by Greg Ewing Aug. 17, 2009

Aug. 17, 2009

Scott David Daniels wrote: > No, I don't really need MT. The others would be fine. > I'd love further details. The one I've been working with is due to Pierre L'Ecuyer [1] and is known as MRG32k3a. It's a combined multiple recursive linear congruential generator with 6 words of state. The formulas are r1[i] = (a12 * r1[i-2] + a13 * r1[i-3]) % m1 r2[i] = (a21 * r2[i-1] + a23 * r2[i-3]) % m2 r[i] = (r1[i] - r2[i]) * m1 where m1 = 2**32 - 209 m2 = 2**32 - 22835 … [View More] a12 = 1403580 a13 = -810728 a21 = 527612 a23 = -1370589 If you consider the state to be made up of two 3-word state vectors, then there are two 3x3 matrices which map a given state onto the next state. So to jump ahead n steps in the sequence, you raise these matrices to the power of n. I've attached some code implementing this generator together with the jumping-ahead. (Sorry it's in C++, I hadn't discovered Python when I wrote it.) [1] Pierre L'Ecuyer, Good Parameters and Implementations for Combined Multiple Recursive Random Number Generators, Operations Research v47 no1 Jan-Feb 1999 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/combmrg2.ps -- Greg /* * cmr_random_generator.C * ====================== * * Combined Multiple Recursive random number generator. * * This is an implementation of Pierre L'Ecuyer's * MRG32k3a generator, described in: * * Pierre L'Ecuyer, Good Parameters and Implementations for * Combined Multiple Recursive Random Number Generators, * Operations Research v47 no1 Jan-Feb 1999 */ #include "cmr_random_generator.H" static const double norm = 2.328306549295728e-10, m1 = 4294967087.0, m2 = 4294944443.0, a12 = 1403580.0, a13 = -810728.0, a21 = 527612.0, a23 = -1370589.0; static double a[2][3][3] = { { {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0}, {a13, a12, 0.0} }, { {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0}, {a23, 0.0, a21} } }; static double m[2] = { m1, m2 }; static double init_s[2][3] = { {1.0, 1.0, 1.0}, {1.0, 1.0, 1.0} }; inline static double mod(double x, double m) { long k = (long)(x / m); x -= k * m; if (x < 0.0) x += m; return x; } /* * Initialisation */ CMRRandomGenerator::CMRRandomGenerator() { for (int i = 0; i <= 1; i++) for (int j = 0; j <= 2; j++) s[i][j] = init_s[i][j]; } /* * Advance CMRG one step and return next number */ double CMRRandomGenerator::Next() { double p1 = mod(a12 * s[0][1] + a13 * s[0][0], m1); s[0][0] = s[0][1]; s[0][1] = s[0][2]; s[0][2] = p1; double p2 = mod(a21 * s[1][2] + a23 * s[1][0], m2); s[1][0] = s[1][1]; s[1][1] = s[1][2]; s[1][2] = p2; double p = p1 - p2; if (p < 0.0) p += m1; return (p + 1) * norm; } typedef unsigned long long Int64; typedef Int64 CMRG_Vector[3]; typedef Int64 CMRG_Matrix[3][3]; static Int64 ftoi(double x, double m) { if (x >= 0.0) return Int64(x); else return Int64((long double)x + (long double)m); } static double itof(Int64 i, Int64 m) { return i; } static void v_ftoi(double u[], CMRG_Vector v, double m) { for (int i = 0; i <= 2; i++) v[i] = ftoi(u[i], m); } static void v_itof(CMRG_Vector u, double v[], Int64 m) { for (int i = 0; i <= 2; i++) v[i] = itof(u[i], m); } static void v_copy(CMRG_Vector u, CMRG_Vector v) { for (int i = 0; i <= 2; i++) v[i] = u[i]; } static void m_ftoi(double a[][3], CMRG_Matrix b, double m) { for (int i = 0; i <= 2; i++) for (int j = 0; j <= 2; j++) b[i][j] = ftoi(a[i][j], m); } static void m_copy(CMRG_Matrix a, CMRG_Matrix b) { for (int i = 0; i <= 2; i++) for (int j = 0; j <= 2; j++) b[i][j] = a[i][j]; } static void mv_mul(CMRG_Matrix a, CMRG_Vector u, CMRG_Vector v, Int64 m) { CMRG_Vector w; int i, j; for (i = 0; i <= 2; i++) { w[i] = 0; for (j = 0; j <= 2; j++) w[i] = (a[i][j] * u[j] + w[i]) % m; } v_copy(w, v); } static void mm_mul(CMRG_Matrix a, CMRG_Matrix b, CMRG_Matrix c, Int64 m) { CMRG_Matrix d; int i, j, k; for (i = 0; i <= 2; i++) { for (j = 0; j <= 2; j++) { d[i][j] = 0; for (k = 0; k <= 2; k++) d[i][j] = (a[i][k] * b[k][j] + d[i][j]) % m; } } m_copy(d, c); } /* * Advance the CMRG by n*2^e steps */ void CMRRandomGenerator::Advance(unsigned long n, unsigned int e) { CMRG_Matrix B[2]; CMRG_Vector S[2]; Int64 M[2]; int i; for (i = 0; i <= 1; i++) { m_ftoi(a[i], B[i], m[i]); v_ftoi(s[i], S[i], m[i]); M[i] = Int64(m[i]); } while (e--) { for (i = 0; i <= 1; i++) mm_mul(B[i], B[i], B[i], M[i]); } while (n) { if (n & 1) for (i = 0; i <= 1; i++) mv_mul(B[i], S[i], S[i], M[i]); n >>= 1; if (n) for (i = 0; i <= 1; i++) mm_mul(B[i], B[i], B[i], M[i]); } for (i = 0; i <= 1; i++) v_itof(S[i], s[i], M[i]); } /* * cmr_random_generator.H * ====================== * * Combined Multiple Recursive random number generator. */ #ifndef cmr_random_generator_H #define cmr_random_generator_H class CMRRandomGenerator { public: CMRRandomGenerator(); double Next(); void Advance(unsigned long mant, unsigned int exp); protected: double s[2][3]; }; #endif [View Less]

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random number generator state
by Scott David Daniels Aug. 16, 2009

Aug. 16, 2009

I find I have a need in randomized testing for a shorter version of getstate, even if it _is_ slower to restore. When running exhaustive tests, a failure report should show the start state of the generator. Unfortunately, our current state includes a 625-element array. I want a state that can be read off a report and typed in to reproduce the state. Something a bit like the initial seed, a count of cycle calls, and a few other things. So, in addition to .getstate() and .setstate(...), I'd … [View More]

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Updating tests in branches
by Frank Wierzbicki Aug. 16, 2009

Aug. 16, 2009

I plan on updating the Python unit tests with tests from Jython that turn out to be generic Python tests. Should I be putting these tests into trunk and 3k or should I also put them into the 2.6 and 3.1 maintenance branches as well? Regards, -Frank

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Tweaking AST lineno and col_offset
by Frank Wierzbicki Aug. 14, 2009

Aug. 14, 2009

Hi all, Off and on I have been directly comparing Jython's AST with Python's AST and generally working towards making them as close to identical as possible. There are a couple of places where I haven't "fixed" Jython because it looks to me like Jython has slightly better offsets. One example: for a,b in c: pass The Tuple node "a,b" ends up with a col_offset of 0 (the position of the "for") where Jython has the col_offset as 4 (the position of "a"). Jython's result is more consistent … [View More]

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(try-except) conditional expression similar to (if-else) conditional (PEP 308)
by Jeff McAninch Aug. 14, 2009

Aug. 14, 2009

I'm new to this list, so please excuse me if this topic has been discussed, but I didn't see anything similar in the archives. I very often want something like a try-except conditional expression similar to the if-else conditional. An example of the proposed syntax might be: x = float(string) except float('nan') or possibly x = float(string) except ValueError float('nan') Here's a simple example: Converting a large list of strings to floats where there may be errors that I want … [View More]

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expy: an expressway to extend Python
by Yingjie Lan Aug. 14, 2009

Aug. 14, 2009

Hi All, This is to announce the initial release of expy 0.1.0. More details at http://expy.sourceforge.net/ Thanks! Yingjie

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Summary of Python tracker Issues
by Python tracker Aug. 14, 2009

Aug. 14, 2009

ACTIVITY SUMMARY (08/07/09 - 08/14/09) Python tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue number. Do NOT respond to this message. 2329 open (+26) / 16195 closed ( +8) / 18524 total (+34) Open issues with patches: 925 Average duration of open issues: 659 days. Median duration of open issues: 414 days. Open Issues Breakdown open 2297 (+26) pending 31 ( +0) Issues Created Or Reopened (34) … [View More]

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Tkinter: modify xview of entry widget
by paolo.fragu＠libero.it Aug. 14, 2009

Aug. 14, 2009

Hi, I'm Paolo from Italy and I'm a python user. I wish to propose a useful and smart method modify in Tkinter Library: Previously to scroll this widget we had to write an external function (recalling xview_moveto and xview_scroll). With my method this operation is cleared and the same as all other widgets (just have to call xview). ---------------------------------------------------------- Modify Proposal: ---------------------------------------------------------- Change the method xview … [View More]

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[RELEASED] Python 3.1.1 Release Candidate
by Benjamin Peterson Aug. 13, 2009

Aug. 13, 2009

On behalf of the Python development team, I'm pleased to announce the first release candidate of Python 3.1.1. This bug fix release fixes many normal bugs and several critical ones including potential data corruption in the io library. The final version should be out within the next week. Python 3.1 focuses on the stabilization and optimization of the features and changes that Python 3.0 introduced. For example, the new I/O system has been rewritten in C for speed. File system APIs that … [View More]

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