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Re: select 1st column element based on criteria in 2nd AND 3rd column

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124501] Re: select 1st column element based on criteria in 2nd AND 3rd column
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sun, 22 Jan 2012 07:19:28 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Your expression doesn't work because its syntax is wrong!

First, there's no such built-in function AND in Mathematica. There is a 
function And, which in the present context you would probably want to 
use by means of its input shortcut &&.

Second, if you use the Slot function (#), you need to construct a pure 
function by terminating with a & symbol.

Thus:

    Select[pairs, 5 >= #[[2]] >= 3 && 10 >= #[[3]] >= 7 &]
{{5, 3, 9}}

For clarity, the above Select expression means the same thing as:

   Select[pairs, (5 >= #[[2]] >= 3 && 10 >= #[[3]] >= 7) &]


On 1/21/12 5:20 AM, hanciong awesome wrote:
> Hello all, suppose I have a table:
>
> pairs = {{1, 3, 4}, {2, 4, 6}, {3, 6, 7}, {4, 1, 8}, {5, 3, 9}, {6, 2,
>      10}, {7, 5, 11}, {8, 2, 13}, {2, 3, 4}, {5, 6, 7}}
>
> how to select rows for which the 2nd column is between 3 and 5, AND
> the 3rd column is between 7 and 10? So I want to do something similar
> to this:
>
> Select[pairs, 5>= #[[2]]>= 3&   AND  10>= #[[3]]>= 7]
>
> but I just couldn't get it to work. what should I do? Thank you
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305



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