condMean works like a very fast version of tapply with FUN=mean.
condMean
FUN=mean
condMean(x, index, na.rm = FALSE, ...)
x
numeric vector to be averaged
numeric
index
(list of) factor(s) for which the mean will be calculated
factor(s)
na.rm
logical If TRUE NA values will be removed
logical
TRUE
NA
...
not used
array with dimensions of index
array