[R] Aggregating dataset to means/day

2011-03-16 Thread OA Fatnes
Hi,

I have a dataset with many observations some days while only one others. I
would like to calculate a mean value per day and then do regression analysis
on the means.

This is what I have:

YearDayTimeherring.density
200747 10.36   2.2
200747 11.50   1.1
200747 14.24   1.4
200766  9.352.5

This is what I want:

YearDay  herring.density
2007 47 1.57
2007 66 2.25

I would also might like to extract means between time 10-16 (h) so that

YearDay  herring.density
2007 471.25

Any idea on how to do this?

I have tried

means07-tapply(herring.density,Day,mean)

Then I get means for every day, but means07 won't fit when plotted against
days, because it is now shorter than Day. I also get a lot of NA values
where there are only 1 observation that day...

Help would be much appreciated!

Cheers,

Ole Andreas

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Re: [R] Aggregating dataset to means/day

2011-03-16 Thread Ivan Calandra

Hi,

Look at ?aggregate.

df - read.table(textConnection(Year Day Time herring.density
2007 47 10.36 2.2
2007 47 11.50 1.1
2007 47 14.24 1.4
2007 66 9.35 2.5), header=TRUE)

You could do this:
aggregate(herring.density~Year+Day, data=df, FUN=mean)

And for the second question:
aggregate(herring.density~Year+Day, data=df[df$Time=10  df$Time=16,], 
FUN=mean)


Alternatively, you can use the function summaryBy in the doBy package. 
You use it exactly the same way as aggregate. You'll only get different 
column names.


HTH,
Ivan


Le 3/16/2011 11:17, OA Fatnes a écrit :

Hi,

I have a dataset with many observations some days while only one others. I
would like to calculate a mean value per day and then do regression analysis
on the means.

This is what I have:

YearDayTimeherring.density
200747 10.36   2.2
200747 11.50   1.1
200747 14.24   1.4
200766  9.352.5

This is what I want:

YearDay  herring.density
2007 47 1.57
2007 66 2.25

I would also might like to extract means between time 10-16 (h) so that

YearDay  herring.density
2007 471.25

Any idea on how to do this?

I have tried

means07-tapply(herring.density,Day,mean)

Then I get means for every day, but means07 won't fit when plotted against
days, because it is now shorter than Day. I also get a lot of NA values
where there are only 1 observation that day...

Help would be much appreciated!

Cheers,

Ole Andreas

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list
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.



--
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calan...@uni-hamburg.de

**
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R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.