7 messages · chris99, Ivan Calandra, Michael Rennie +4 more
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!
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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 ?crit :
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. S?ugetiere Martin-Luther-King-Platz 3 D-20146 Hamburg, GERMANY +49(0)40 42838 6231 ivan.calandra at uni-hamburg.de ********** http://www.for771.uni-bonn.de http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php
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Nice thing about R is there are a number of ways to do things:
x
identifier quantity 1 1 10 2 1 20 3 2 30 4 1 15 5 2 10 6 3 20
require(sqldf)
sqldf('select identifier, sum(quantity) as quantity from x group by identifier')
identifier quantity 1 1 45 2 2 40 3 3 20
or using 'data.table'
require(data.table)
Loading required package: data.table
x <- data.table(x) x[, sum(quantity), by = identifier]
identifier V1 [1,] 1 45 [2,] 2 40 [3,] 3 20
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! -- View this message in context: http://r.789695.n4.nabble.com/Help-summarizing-R-data-frame-tp3069624p3069624.html Sent from the R help mailing list archive at Nabble.com.
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Jim Holtman Data Munger Guru What is the problem that you are trying to solve?
Here are some examples with tapply, aggregate, ddply:
x <- read.table("clipboard", head=TRUE)
with(x, tapply(quantity, identifier, sum))
aggregate(x$quantity, by=list(x$identifier), sum)
aggregate(quantity ~ identifier, data = x, sum)
library(plyr)
ddply(x, .(identifier), summarise, quantity=sum(quantity))
HTH
Patrick
Am 02.12.2010 17:24, schrieb chris99:
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!
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