Help to count in apply(...)

Thanks Robert

the problem (on your example) this I need

ID <- rep(1:10, each=10)
K <- runif(100)
areaFe <- as.data.frame(cbind(ID, K))
#find the max value in each ID area

fer.conc.max <- tapply(areaFe$K, areaFe$ID, max, na.rm=TRUE)
fer.conc.max

??????? 1???????? 2???????? 3???????? 4???????? 5???????? 6
7???????? 8
0.9339687 0.9413441 0.9605550 0.9968569 0.9647085 0.9563837 0.9731356
0.9278238
??????? 9??????? 10
0.9496833 0.9111127
#count the?value?below or equal the fe.comc.max

tapply(areaFe$K <= fer.conc.max, areaFe$ID, sum, na.rm=TRUE)

Error tapply(areaFe$K <= fer.conc.max, areaFe$ID, sum, na.rm = TRUE) :
? dims [product 10] do not match the length of object [100]



2009/3/13 Robert Hijmans <r.hijmans at gmail.com>

Dear Gianni,

I think you want this:

tapply(areaFe$K <= fer.conc.max, areaFe$ID, sum, na.rm=TRUE)

E.g.:

ID <- rep(1:10, each=10)
K <- runif(100)
areaFe <- as.data.frame(cbind(ID, K))
fer.conc.max <- 0.5
tapply(areaFe$K <= fer.conc.max, areaFe$ID, sum, na.rm=TRUE)


Robert


On Fri, Mar 13, 2009 at 9:58 AM, gianni lavaredo
<gianni.lavaredo at gmail.com> wrote:

dear User

I'm quite new to R and trying to learn the basic and sorry for the
email. I
don't wish abuse of mail-list. I had read manual and Help online about
tapply (...). I have a data frame and I need "count" the Fe value with
sum
for every ID sample area

fer.conc.max <- tapply(areaFe$K, areaFe$ID, max, na.rm=TRUE)

I need to count the Fe area with Fe$K <= ?fer.conc.max

# give me the summatory and not the count
fer.conc.max <- tapply(areaFe$K, areaFe$ID, sum, na.rm=TRUE)

I tried sever combination that I found in mail-list archive but alway I
have
a error message

thanks Gianni

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