From: Hvidberg, Martin <mhv_at_dmu.dk>

Date: Tue, 10 Jun 2008 15:05:41 +0200

+45 46 30 12 14

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 10 Jun 2008 - 14:12:23 GMT

Date: Tue, 10 Jun 2008 15:05:41 +0200

I have a data set something like this:

> dafSamp <- data.frame(cbind(c(1972,1984,1969,1976,1999,1996,1976,1984,1976),c(117,73,92,113,80,78,98,106,99)))

The real dataset is of cause much larger, app. 100.000 samples

I can make the averages like this:

> Ag <- mean(dafSamp[,2])

*> Ag
*

> Ay <- aggregate(x=dafSamp[,2], by=list(dafSamp[,1]), FUN='mean')

*> Ay
*

To see how many samples from each year I could write:

> Cy <- aggregate(x=dafSamp[,2], by=list(dafSamp[,1]), FUN='length')

*> Cy
*

Group.1 x

1 1969 1

2 1972 1

3 1976 3

4 1984 2

5 1996 1

6 1999 1

I would like to create a new vector with the adjusted values (dafSmap[,2] * Ay(for a relevant year) / Ag)

I tried to write:

vecAA <- dafSamp[,2] * Ay[which(Ay[,1]==dafSamp[,1]),2] / Ag

but the result is all NAs :-( Might have seen that coming, Not the same length...

Question: How do I go about making such calculation?

:-) Martin Hvidberg

Here is the code in full, if you want to try it...

dafSamp <- data.frame(cbind(c(1972,1984,1969,1976,1999,1996,1976,1984,1976),c(117,73,92,113,80,78,98,106,99)))

Ag <- mean(dafSamp[,2])

Ag

Ay <- aggregate(x=dafSamp[,2], by=list(dafSamp[,1]), FUN='mean')

Ay

Cy <- aggregate(x=dafSamp[,2], by=list(dafSamp[,1]), FUN='length')

Cy

vecAA <- dafSamp[,2] * Ay[which(Ay[,1]==dafSamp[,1]),2] / Ag

University of Aarhus <http://www.au.dk/en> Danmarks Miljøundersøgelser <http://www.dmu.dk/>

Hvidberg, Martin <http://www2.dmu.dk/1_Om_DMU/2_medarbejdere/cv/employee2_NH.asp?PersonID=MHV>
Senior Geographer (Climatology, Spatial modeling) <http://www.geogr.ku.dk/>
N 55°41m43.48s E 12°06m05.13s ETRS89

National Environmental Research Inst. <http://www.dmu.dk/International/>
P.O. Box 358

Frederiksborgvej 399

DK-4000 Roskilde

Martin.Hvidberg_at_dmu.dk

www.dmu.dk/AtmosphericEnvironment/ tel: fax: +45 46 30 11 55

+45 46 30 12 14

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