Re: Selecting Many Things Rather Than Selecting One Thing From Many

• To: mathgroup at smc.vnet.net
• Subject: [mg66198] Re: Selecting Many Things Rather Than Selecting One Thing From Many
• From: dh <dh at metrohm.ch>
• Date: Thu, 4 May 2006 05:19:41 -0400 (EDT)
• References: <e39k7e\$cno\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi Gregory,
try:
Select[theMatrix, MemberQ[K,#[[1]]]& ]

Daniel

Gregory Lypny wrote:
> Hello everyone,
>
> I've discovered another use or need for the Select function, which I
> suspect requires mapping of some sort.
>
> In my previous posts, members of this MathGroup kindly showed me how
> to apply Select to many columns of a matrix at once.  For example,
>
> (Select[#1, #1 > K & ] & ) /@ Transpose[theMatrix]
>
> will pull out all values greater than K, where K is a number such as
> 100.
>
> But suppose now that K is a list of numbers, such as K={34, 876,
> 199}, and I simply want to extract or identify all of the rows in the
> first column of theMatrix equal to any one of those numbers.  How
> would I do that?  I started with
>
> Select[theMatrix, #[[1]]==any element of list K]
>
> and I imagine something similar could be applied to the Position
> function.
>
> Any hint would be much appreciated.
>
> 	Gregory
>

```

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