[R] Help summarizing R data frame

[Ivan Calandra]

see ?aggregate, and ?summaryBy (in package doBy)
I think ddply (in package plyr) could also do the job

Ivan

Le 12/2/2010 17:24, chris99 a écrit :
> I am trying to aggregate data in column 2 to identifiers in col 1
>
> eg..
>
> take this>
>
> identifier       quantity
> 1                     10
> 1                     20
> 2                     30
> 1                     15
> 2                     10
> 3                     20
>
> and make this>
>
> identifier         quantity
> 1                    45
> 2                    40
> 3                    20
>
>
> Thanks in advance for your help!

-- 
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.calandra at uni-hamburg.de

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