Re: put some elements to zero
- To: mathgroup at smc.vnet.net
- Subject: [mg101491] Re: put some elements to zero
- From: dr DanW <dmaxwarren at gmail.com>
- Date: Wed, 8 Jul 2009 07:13:59 -0400 (EDT)
- References: <h2vcj8$qq7$1@smc.vnet.net>
At it's heart, Mathematica is a very efficient pattern matcher, so if
you can think of a pattern that matches only the expressions you want
to effect, then take advantage of the built-in matching system. Your
criteria are pretty clearly spelled out already, so the code writes
itself, for example:
table /. {(xi_)?(# < 0.5 &), yi_} :> {xi, 0}
or
table /. {xi_, yi_} :> {xi, 0} /; xi < 0.5
Some people who are not used to the programming-with-punctuation style
may prefer the partially spelled-out version:
ReplaceAll[table, {xi_, yi_} :> Condition[{xi, 0}, xi < 0.5]]
Look up tutorial/PuttingConstraintsOnPatterns in the Documentation
Center.