eval.hyper: Evaluate an Expression in Each Row of a Hyperframe
Description
An expression, involving the names of columns in a hyperframe,
is evaluated separately for each row of the hyperframe.
Usage
eval.hyper(e, h, simplify = TRUE, ee = NULL)
Arguments
e
An Rlanguage expression to be evaluated.
h
A hyperframe (object of class "hyperframe")
containing data.
simplify
Logical. If TRUE, the return value
will be simplified to a vector whenever possible.
ee
Alternative form of e. See Details.
Value
Normally a list of length
$n$ (where $n$ is the number of rows) containing the results
of evaluating the expression for each row.
If simplify=TRUE and each result is a single atomic value,
then the result is a vector or factor
containing the same values.
Details
This function evaluates the expression e in each row
of the hyperframe h.
The argument e should be an Rlanguage expression
in which each variable name is either the name of a column in the
hyperframe h, or the name of an object in the global environment.
For each row of h, the expression will be evaluated
so that variables which are column names of h are
interpreted as the entries for those columns in the current row.
For example, if h has columns called A and B,
then eval.hyper(A != B, h) inspects each row of h in turn,
tests whether the entries in columns A and B are
equal, and returns the $n$ logical values.