map: Map One Set of Values to Another
In metrumresearchgroup/metrumrg: Pharmacometric Tools for Data Preparation, Modeling, Simulation, and Reporting

Description Usage Arguments Details Value Author(s) References See Also Examples

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

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

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

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.

vector of same class as to and same length as x

Tim Bergsma

http://metrumrg.googlecode.com

match

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