map: Map One Set of Values to Another

In metrumrg: Pharmacometric Tools for Data Preparation, Modeling, Simulation, and Reporting

Description

Systematically substitute specific values from one set using corresponding values from another set.

Usage

map(x, from, to, strict=TRUE, ...)

Arguments

x	vector
from	vector (elements usually unique)
to	vector with same length as from
strict	whether to set unmapped values to NA (default)
...	ignored

Details

Occasionally one wants to recode a set of categories using some other idiom. factor supports recoding by creative use of the arguments levels and labels. However, the result is a factor, and may need more transformation. Furthermore, factor allows one-to-one reclassification but not many-to-one reclassification (repeated levels is not supported; i.e., it is not directly possible to collapse two levels to a single replacement code).

Here, from is the discrete set of values we expect in x, and to is the element-wise corresponding values with which we wish to re-present elements in x. Values in x not found in from will be normally represented as NA (which is itself a legitimate value for to). However, if strict=FALSE, map tries to preserve un-mapped values.

It is an error if from and to have different lengths.

Value

vector of same class as to and same length as x

Author(s)

Tim Bergsma

References

http://metrumrg.googlecode.com

See Also

• match

Examples

map(
	c('white','Asian','Indian'),
	from=c('white','White','black','Black','asian','Asian'),
	to=  c(   1,      1,      2,      2,      3,      3   )
)

metrumrg documentation built on May 2, 2019, 5:55 p.m.