Problem with Position applied on 2D list?

*To*: mathgroup at smc.vnet.net*Subject*: [mg72570] Problem with Position applied on 2D list?*From*: Heiko Damerau <heiko.damerau.news at cern.ch>*Date*: Thu, 11 Jan 2007 01:56:11 -0500 (EST)

Dear All, There is some strange behaviour of the Position[] function I am struggling with: integerRandomTable = Table[Table[Random[Integer, 10], {10}], {10}]; Find the position of all lists containing the value 5 (just a simple example): Position[integerRandomTable, _?(MemberQ[#, 5] &)] gives the expected result, e.g. {{1}, {3}, {4}, {5}, {6}, {7}, {8}}. However, just asking for all lists not containing the value 5 Position[integerRandomTable, _?(Not[MemberQ[#, 5]] &)] Doesn't give the expected result but some strange thing, e.g. {{0}, {1,0}, {1, 1}, {1, 2}, {1, 3}, {1, 4}, ..., {10, 3}, {10, 4}, {10, 5}, {10, 6}, {10, 7}, {10, 8}, {10, 9}, {10, 10}, {10}, {}} What is the explanation for the different behaviour of MemberQ[] and Not[MemberQ[]]? Thanks a lot in advance for any help. Best regards, Heiko

**Follow-Ups**:**Re: Problem with Position applied on 2D list?***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>