Update the data variables in a survey design, either with a formula for a new set of variables or with an expression for variables to be added.
a survey design object
tag=expr add a new variable
computed by evaluating
expr in the survey data.
Database-backed objects may not have write access to the database and so
update does not attempt to modify the database. The expressions
are stored and are evaluated when the data is loaded.
If a set of new variables will be used extensively it may be more efficient to modify the database, either with SQL queries from the R interface or separately. One useful intermediate approach is to create a table with the new variables and a view that joins this table to the table of existing variables.
There is now a base-R function
transform for adding new
variables to a data frame, so I have added
transform as a synonym for
update for survey objects.
A survey design object