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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