Hello,
Try instead
sMean2 <- tapply(parameter[[Pname]], parameter[[Iname]], mean)
Hope this helps,
Rui Barradas
Em 04-03-2014 17:01, Barry King escreveu:
I am reading parameters from an Excel file but am having trouble using them
in tapply. Here is a mini-version of my problem.
------------------------------------------------------------------------------------------------------------------------------------------------
sorted <- data.frame(c("Single","Single","Double","Double","Double",
"Triple"),
c(324.5, 435.3, 568.3, 345.4, 143.5, 563.5))
colnames(sorted) <- c("ITEM","PRICE")
attach(sorted)
sMean <- tapply(PRICE,ITEM,mean) # works but cannot use column names
directly
# since reading them from an Excel file
into
# a parameter file
Pname <- c("PRICE")
Iname <- c("ITEM")
parameter <- data.frame(Pname,Iname) # This mimics reading the specific
column names
# from Excel
# Now I want to indirectly reference the PRICE and ITEM columns but this
does
# not work as expected
sMean2 <- tapply(parameter$Pname, parameter$Iname, mean)
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