| transform {base} | R Documentation |
Transform an Object, for Example a Data Frame
Description
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 transform.data.frame.
Usage
transform(`_data`, ...)
Arguments
_data |
The object to be transformed |
... |
Further arguments of the form |
Details
The ... 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 _data.
Value
The modified value of _data.
Warning
This is a convenience function intended for use interactively. For
programming it is better to use the standard subsetting arithmetic functions,
and in particular the non-standard evaluation of
argument transform can have unanticipated consequences.
Note
If some of the values are not vectors of the appropriate length, you deserve whatever you get!
Author(s)
Peter Dalgaard
See Also
within for a more flexible approach,
subset,
list,
data.frame
Examples
transform(airquality, Ozone = -Ozone)
transform(airquality, new = -Ozone, Temp = (Temp-32)/1.8)
attach(airquality)
transform(Ozone, logOzone = log(Ozone)) # marginally interesting ...
detach(airquality)