[R] calculations with vectors of unequal length
e.hofstadler at gmail.com
Wed Apr 27 14:25:37 CEST 2011
Great, many thanks to Scott and Petr!
2011/4/27 Petr PIKAL <petr.pikal at precheza.cz>:
> r-help-bounces at r-project.org napsal dne 27.04.2011 13:30:13:
>> Hi there,
>> this is probably simple but I can't seem to figure it out by myself...
>> I have two dataframes (df.1 and df.2):
>> df.1 <- data.frame(year=factor(rep(1:3,3)), level=rep(letters[1:3],3),
>> df.2 <- data.frame(year=factor(c(1:5)), number=c(21:25))
>> I would like to create a new variable df.1$new, which is supposed to
>> be the sum of each element of df.1$number and those elements of
>> df.2$number, where df.2$year equals df.1$year.
> merge(df.1,df.2, by.x="year", by.y="year", all.x=T)
> year level number.x number.y
> 1 1 a 11 21
> 2 1 a 17 21
> 3 1 a 14 21
> than you can sum last 2 columns. I believe that sqldf package can do what
> you want more efficiently but I do not use it so I do not know exact
>> What would be the most efficient way of doing this?
>> R-help at r-project.org mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
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