feat: add randomSeed argument to COIN_CMD for reproducible CBC solves (#613) - #936
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haiiibin wants to merge 1 commit into
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feat: add randomSeed argument to COIN_CMD for reproducible CBC solves (#613)#936haiiibin wants to merge 1 commit into
haiiibin wants to merge 1 commit into
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COIN_CMD exposes threads, maxNodes, timeMode, etc. as constructor arguments that map to CBC command-line options, but the random seed (CBC's -randomSeed) could previously only be set through the generic `options` list. Controlling the seed is the standard way to make MIP solves reproducible (and can also change solve time), so expose it directly. Add a randomSeed keyword argument that flows into optionsDict and is emitted as `-randomSeed <n>` via getOptions, mirroring the existing threads/maxNodes handling. (PULP_CBC_CMD was removed, so COIN_CMD, the default CBC entry point, is where this belongs.) Add a test mirroring test_strong that solves with a seed and asserts -randomSeed appears on the command line.
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Motivation
COIN_CMDalready exposesthreads,maxNodes,timeMode,gapRel, etc. as constructor arguments that translate to CBC command-line options, but the random seed (CBC's-randomSeed) could previously only be set through the genericoptionslist, e.g.COIN_CMD(options=["randomSeed 20"]). Setting the seed is the standard way to make MIP solves reproducible (and can also change solve time), so it is worth exposing directly. This was requested in #613 and seconded there by a contributor.Change
randomSeedkeyword argument toCOIN_CMD.__init__. It flows intooptionsDictlike the other options and is emitted as-randomSeed <n>fromgetOptions, mirroring the existingthreads/maxNodeshandling.PULP_CBC_CMD, but that class no longer exists;COIN_CMDis the current CBC entry point (and the default solver), so the argument lives there.Verification
-randomSeed <n>and solves to optimality (against PuLP's CBC binary).getOptions()emitsrandomSeed 20whenrandomSeed=20is set, so-randomSeed 20appears on the solver command line.test_random_seed(inCOIN_CMD_CBCOptionsTest) mirroring the existingtest_strong: it solves a small MIP with a seed, reads the command line back from the log file, and asserts-randomSeed 20is present; it also asserts the constructor argument populatesoptionsDict.Closes #613.