From: Don MacQueen <macq_at_llnl.gov>

Date: Tue 14 Feb 2006 - 02:38:42 EST

Date: Tue 14 Feb 2006 - 02:38:42 EST

There is a function in the Hmisc package that will help.

Example:

*> require(Hmisc)
*

> x <- sort(runif(10))

*> x
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[1] 0.1225542 0.1620869 0.2197772 0.3187375 0.5498879 0.5644445
0.5812717 0.7380532 0.8187384 0.9063713

*> whichClosest(x,.41)
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[1] 4

*> x[4]
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[1] 0.3187375

Or for your matrix (yourmat), this should work (but I haven't tested it)

yourmat[ whichClosest(yourmat[,'X'] , -0.6523) , 'Y']

-Don

At 1:30 PM +0100 2/13/06, Ita.Cirovic-Donev@hypo-alpe-adria.com wrote:

*>Hi!
**>
*

>I have a problem of finding a specific value in a column. For example, I

*>have a matrix with say 2 columns
**>
**> X Y
**>1 -2.0341602 9.036689e-05
**>2 -1.4287230 1.807338e-04
**>3 -1.1194402 2.711007e-04
**>4 -1.0327582 3.614676e-04
**>5 -0.8130556 4.518344e-04
**>6 -0.7138212 5.422013e-04
**>7 -0.6634425 6.325682e-04
**>8 -0.6512083 7.229351e-04
**>9 -0.6176286 8.133020e-04
**>10 -0.5897241 9.036689e-04
**>
**>Now if I have some value of x=-0.6523. I need to find a value in the X
**>column that is the closest to my value of x then read off the row number
**>and then take the corresponding value in column Y. What I am not sure is
**>how to do the first search where I would search by decimal places and take
**>the smallest absolute distance between the numbers. For example if he finds
**>the first value which is correct in this case - and then 0 and then 6 and
**>then 5 but now there is no 2 for that specific decimal place so he would
**>calculate the distance between the one before and the one after and see
**>which one is smaller. For that which is smaller would be the final X value.
**>Can someone please give me a hint on how to proceed. Thanks.
**>
**>______________________________________________
**>R-help@stat.math.ethz.ch mailing list
**>https://stat.ethz.ch/mailman/listinfo/r-help
**>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
*

-- -------------------------------------- Don MacQueen Environmental Protection Department Lawrence Livermore National Laboratory Livermore, CA, USA ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Tue Feb 14 02:47:25 2006

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