lapply on an object and return a data.frame.fun on each element of input x
and combines the results as data.frame columns.
The results will get replicated to have equal length
if necessary and possible.
dapply(x, fun, ..., col.names)data.frame]
Data frame.function]
The function to apply.fun.character(1)]
Column names for result.
Default are the names of x.data.frame].