MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Selecting Rows Based on Column Values

  • To: mathgroup at smc.vnet.net
  • Subject: [mg101540] Re: [mg101471] Selecting Rows Based on Column Values
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Thu, 9 Jul 2009 02:00:25 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

Select[tester, #[[3]] == 1 &]

Cases[tester, _?(#[[3]] == 1 &)]

Select[tester, Last[#] == 1 &]

Cases[tester, _?(Last[#] == 1 &)]

Cases[tester, {_, _, 1}]

DeleteCases[tester, {_, _, Except[1]}]

tester /. {_, _, Except[1]} -> Sequence[]


Bob Hanlon

---- cynthia wu <wu.x.cynthia at gmail.com> wrote: 

=============
I've been trying to use the Select Command to select only the rows
that have the a specific value in a specific column.  I have, for
example, the following matrix (4x3):

tester={{1, 3, 1}, {3, 1, 0}, {4, 2, 1}, {5, 6, 2}}

I want to select the rows that have values ==1 in the 3rd column.
I've tried:

select(tester, #[[All,3]]==1&), but I get an error saying that my
request violates the matrix boundaries.

The desired output should be: {{1,3,1}, {4,2,1}}.

Any thoughts would be greatly appreciated.  Thanks!




  • Prev by Date: Re: Manipulating list
  • Next by Date: Re: Selecting Rows Based on Column Values
  • Previous by thread: Re: Selecting Rows Based on Column Values
  • Next by thread: Re: Selecting Rows Based on Column Values