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MathGroup Archive 2006

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Re: Count Function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg65532] Re: [mg65501] Count Function
  • From: bsyehuda at gmail.com
  • Date: Thu, 6 Apr 2006 06:52:46 -0400 (EDT)
  • References: <200604051055.GAA21742@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

The pattern matching capabilities of Mathematica will save your life many
time. You just need to know how to ask this salvage
So,
you need a pattern represented by _
and you want that pattern to give true for some condition, so write an
intrinsic function that will return True if the value is greater than, say,
-9
#>-9& is the function
Now, to make the pattern use that function you need to use ?
and as a command with Count
Count[X[[All,14]],_?(#>-9&)]

Note that the & sign should be enclosed within the parentheses

regards
yehuda

On 4/5/06, Gregory Lypny <gregory.lypny at videotron.ca> wrote:
>
> The syntax will be the death of me.
>
> Count[X[[All,14]], -9.] will tally how many elements in column 14 of
> matrix X are equal to -9, but I can't for the life of me figure out
> how to get how many are greater than -9.  Any hint would be most
> appreciated.
>
>         Greg
>
>
>



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