## S3 method for class 'data.table':
transform(`_data`, \ldots)
## S3 method for class 'data.table':
within(data, expr, \ldots)
Arguments
data, _data
data.table to be transformed.
...
for transform, Further arguments of the form
tag=value. Ignored for within.
expr
expression to be evaluated within the data.table.
Value
The modified value of data.
Details
within is like with, but modifications (columns changed,
added, or removed) are updated in the returned data.table.
Note that transform will keep the key of the
data.table provided the ``targets'' of the transform (i.e. the
columns that appear in ...) are not in the key of the data.table.
within also retains the key provided the key columns are not ``touched''.