I've just added a version of the improvements to R-devel. After some
discussion, we decided this should be a new function, not just a new arg
to sapply, and I chose vapply from among the 52 different suggestions
that were offered.
The usage is
vapply(X, FUN, FUN.VALUE, ..., USE.NAMES = TRUE)
and some extracts from the docs say:
‘vapply’ is similar to ‘sapply’, but has a pre-specified
type of return value, so it can be safer (and sometimes faster) to
use.
...
Simplification is always done in ‘vapply’. This function
checks that all values of ‘FUN’ are compatible with the
‘FUN.VALUE’, in that they must have the same length and type.
(Types may be promoted to a higher type within the ordering
logical < integer < real < complex, but not demoted.)
...
‘vapply’ returns a vector or matrix of type matching the
‘FUN.VALUE’. If ‘length(FUN.VALUE) != 1’ a matrix will be
returned with ‘length(FUN.VALUE)’ rows and ‘length(X)’
columns, otherwise a vector of the same length as ‘X’. Names
of rows in the matrix value are taken from the ‘FUN.VALUE’ if
it is named, otherwise from the result of the first function call.
Column names of the matrix value or names of the vector value are
set from ‘X’ as in ‘sapply’.
Thanks for suggesting this.
Duncan Murdoch
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