Find elements of Rd objects for which a condition is true

Find elements of Rd objects for which a condition is true.

Usage

Rdo_which(rdo, fun)

Rdo_which_tag_eq(rdo, tag)

Rdo_which_tag_in(rdo, tags)

Arguments

rdo: an Rd object.
fun: a function to evaluate with each element of rdo.
tag: a character string.
tags: a character vector.

Details

These functions return the indices of the (top level) elements of rdo which satisfy a condition.

Rdo_which finds elements of rdo for which the function fun gives TRUE.

Rdo_which_tag_eq finds elements with a specific Rd_tag.

Rdo_which_tag_in finds elements whose Rd_tag's are among the ones specified by tags.

Value

a vector of positive integers

Author

Georgi N. Boshnakov

Examples

## get the help page for topoc seq()
rdo_seq <- tools::Rd_db("base")[["seq.Rd"]]
## find location of aliases in the topic
( ind <- Rdo_which_tag_eq(rdo_seq, "\alias") )
#> integer(0)
## extract the first alias
rdo_seq[[ ind[1] ]]
#> NULL
if (FALSE) {
## extract all aliases
rdo_seq[ind]
}

## db_bibtex <- tools::Rd_db("bibtex")
## names(db_bibtex)
## ## Rdo object for read.bib()
## rdo_read.bib <- db_bibtex[["read.bib.Rd"]]
## Rdo_tags(rdo_read.bib)
## 
## ## which elements of read.bib are aliases?
## Rdo_which_tag_eq(rdo_read.bib, "\alias")
## rdo_read.bib[[3]]
## 
## ## which elements of read.bib contain R code?
## Rdo_which(rdo_read.bib, function(x) any(Rdo_tags(x) == "RCODE") )
## rdo_read.bib[[5]]
## ## which contain prose?
## Rdo_which(rdo_read.bib, function(x) any(Rdo_tags(x) == "TEXT") )