This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
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FilterRules

FilterRules[rules, patt]
filters the list rules by picking out only those rules whose left-hand sides match patt.
FilterRules[rules, {patt1, patt2, ...}]
picks out rules whose left-hand sides match any of the patti.
  • The rules in the list rules can be either -> or :> rules.
  • If any of the patti is a rule of the form lhs->rhs, then it is treated just as lhs.
  • If patti is a string, it will also match a symbol whose name is the string.
  • FilterRules[rules, Except[patt]] gives all rules except those whose left-hand sides match patt.
New in 6