formulas: Internal formula term manipulation functions

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

Description

These are helper function used in the formula interface of varComp and varComp.test. They either sort or split the formula terms involving ":".

Usage

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callList2terms(cl)
splitTerm(term)
sortTerm(term, priority)

Arguments

cl

A list converted from a call.

term

A character scalar of a formula term to be re-ordered alphanumerically with respect to the components separated by ":".

priority

A character vector whose elements have higher priority to be ordered to the front of the term.

Details

The main use of sortTerm is to transform an interaction term like "B:A" into ordered form "A:B" such that redundant terms are easier to be identified. The results will depend on the system locale.

Value

callList2terms returns a character vector of individual terms (possibly with duplicates). splitTerm returns a character vector of unique individual components in the term. sortTerm returns a character scalar with individual components sorted.

Author(s)

Long Qu

See Also

stats::formula

Examples

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sortTerm("sex:ibs(SNP)")  ## ibs(SNP) is moved to the front in most locales
sortTerm("sex:ibs(SNP)", "sex")  ## the same as input
splitTerm("sex:ibs(SNP)")	## two components
sortTerm("ns(x, df=3):a:b:ibs(SNP)", "b")  

varComp documentation built on May 19, 2017, 2:50 p.m.

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