[R] Odp: calculations with vectors of unequal length
petr.pikal at precheza.cz
Wed Apr 27 14:04:59 CEST 2011
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?
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> and provide commented, minimal, self-contained, reproducible code.
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