Cases to Select ?
- To: mathgroup at smc.vnet.net
- Subject: [mg73920] Cases to Select ?
- From: Mr Ajit Sen <senra99 at yahoo.co.uk>
- Date: Sat, 3 Mar 2007 01:02:02 -0500 (EST)
Dear MathGroup,
Consider the following list:
A={{1, 4, 5}, {3, -6, 1}, { 2, 0, 4}, {4, 3, 8},
{-5, 1, 4}, {3, 7, 4},{4,6,0,3}, {-3, 4, 3, 8, 1}}
To retrieve those sublists containing 3 and 4, I'm
using
A34C=Cases[A, {___, 4, ___, 3, ___} | {___, 3, ___,
4, ___}].
My first query is whether there is a (neater ?) way
to combine the 2 patterns, possibly using MemberQ as
in
A34S=Select[A, MemberQ[#, 3] && MemberQ[#, 4] &] .
Now, say I'd like to pick out those sublists that do
not contain 3 and 4. Then I don't get the result
{3,-6,1} with
NotA34S=Select[A, (FreeQ[#, 3] && FreeQ[#, 4]) &]
nor with
Select[A, (FreeQ[#, 3] || FreeQ[#, 4]) &]
nor with
Complement[A,A34S]
Why not? I don't think !MemberQ exists. Looking at
all negations in the Help browser, I guess that Unsame
could do the trick but am unable to apply it.
Finally, how could I do it using Cases
NotA34C= Cases[A, pattern??] ?
Thank you very much for your help.
Ajit Sen.
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- From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
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