scope: Scoped Evaluation
In patperry/r-frame: Flexible Data Frames

Description Usage Arguments Details Value See Also Examples

Evaluate an expression in the context of a data environment.

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scope(x, expr, envir = NULL)

scopeQuoted(x, expr, envir = NULL)

`x`	a list or data object.
`expr`	an object to be evaluated.
`envir`	an enclosing environment, or `NULL` for the calling frame.

The scopeQuoted evaluates its expr argument in a context that by default looks for names first in x and then in envir. If the expression contains a call to I() then the argument of that call gets evaluatedc in the environment envir, not in x.

The scope function quotes its expr argument and then calls scopeQuoted.

The scope evaluation mechanism gets used in all functions in the ‘frame’ package that require non-standard evaluation. It is similar to the evaluation mechanism used by the model.frame function, but is otherwise not used in base R.

The result of the evaluated expression expr.

select, transform.dataset.

x <- list(a = 1:10, b = 10 * (1:10))
a <- 100000000
c <- 1000

# look up first in 'x', then in the calling environment
scope(x, a * b + c)

# look up 'a' in the calling environment, not in 'x'
scope(x, I(a) * b + c)

# evaluate a quoted expression
scopeQuoted(x, quote(a + c)) # equivalent to scope(x, a + c)