[R] Applying "by" results

[Jan_Svatos@eurotel.cz]

Hi Dieter,

> PPress$Press<-unlist(by (Press,list(Marker,Chan), function(x) x-min(x)))

does the magic.
BTW, I have had similar problem and unlist is quite useful for solving such
kind of tasks.

Best,
Jan

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/- Jan Svatos,              Sokolovska 855/225 -/
/- Data Analyst,            Prague 9           -/
/- Eurotel Praha            190 00             -/
/- jan_svatos at eurotel.cz    Czechia            -/
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- - - Original message: - - -
From: owner-r-help at stat.math.ethz.ch
Send: 7/29/01 3:55:58 PM
To: "R-Help" <r-help at lists.r-project.org>
Subject: [R] Applying "by" results

I want to subtract the group minumum of the value in each group
from the indidvidual values, replacing the original values of Press
(something like a groupwise sweep).

This almost works:

#-----------------------------------
PPress<-data.frame(Marker=as.factor(c(rep(1,12),rep(2,12))),
                   Chan=as.factor(rep(1:4,6)), Press=rnorm(24) )
attach(PPress)
by (Press,list(Marker,Chan), function(x) x-min(x))
#-------------------------------------

The data printed out those I need, but how do I
get these back into to PPress?


---------------------------------------
Dr. Dieter Menne
Biomed Software
72074 Tübingen
Tel (49) (7071) 52176
FAX (49) (7071) 55 10 46
dieter.menne at menne-biomed.de
www.menne-biomed.de

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