Pattern matching
- To: mathgroup at smc.vnet.net
- Subject: [mg4881] Pattern matching
- From: xharkrvs at mbox.tu-graz.ac.at (Reinhard Simonovits)
- Date: Thu, 26 Sep 1996 22:42:31 -0400
- Organization: Graz University of Technology, Austria
- Sender: owner-wri-mathgroup at wolfram.com
Dear Mathgroupers,
In the list of two dim vectors vecs = { { {-1,1}, {2,2} }, {3,4} } in a rectangular coord systems, the last
vector is a radius vector.
To plot them I have to add {0,0}, so that plotvecs = { { {-1,1}, {2,2} }, { {0,0}, {3,4} } } fulfills the task.
This can be done with
plotvecs = Apply[ If[ NumberQ[#1], { {0,0}, {##} }, {#1,#2} ]&, vecs, {1} ]
I wonder how could this be done by pattern matching.
plotvecs = vecs /. {a_,b_} -> { {0,0},{a,b} } /; ???
Thanks in advance, Reinhard
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