transform is a generic function, which---at least currently---only does anything useful with data frames.
transform.default converts its first argument to a data frame if possible and calls
- The object to be transformed
- Further arguments of the form
... arguments to
transform.data.frame are tagged vector expressions, which are evaluated in the data frame
_data. The tags are matched against
names(_data), and for those that match, the value replace the corresponding variable in
_data, and the others are appended to
The modified value of
Prior to R 2.3.0, the first argument was named
x, but this caused trouble if people wanted to create a variable of that name. Names starting with an underscore are syntactically invalid, so the current choice should be less problematic.
If some of the values are not vectors of the appropriate length, you deserve whatever you get!
Documentation reproduced from R 2.15.3. License: GPL-2.