# Internal formula term manipulation functions

### 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

1 2 3 | ```
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

1 2 3 4 |