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2D pattern matching

• To: mathgroup at smc.vnet.net
• Subject: [mg77140] 2D pattern matching
• From: "alexxx.magni at gmail.com" <alexxx.magni at gmail.com>
• Date: Tue, 5 Jun 2007 06:24:23 -0400 (EDT)

hi everybody,

do you know how to do a pattern match involving 2D matrices?
If e.g. you have a list

a = {{0, 0, 0, 0, 0, 0}, {0, 1, 0, 0, 0, 0}, {0, 1, 0, 1, 1, 0}, {0,
   0, 0, 1, 1, 0}, {0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0}}

i.e.
0 0 0 0 0 0
0 1 0 0 0 0
0 1 0 1 1 0
0 0 0 1 1 0
0 0 0 0 0 0

is it possible for me to write a rule by which I am able to find the
2x2 square of 1's, and replace it with something else?

I studied all I could on patterns, but didnt find an answer...

thanks for ANY help

Alessandro Magni

• Follow-Ups:
  • Re: 2D pattern matching
    • From: János <janos.lobb@yale.edu>