Parse R documentation

Source: R/parseRd.R

Modified version of tools:::.Rd_get_metadata() that keeps whitespace and returns character instead of matrix.

parseRd(object, tag)

Arguments

object

Rd. R documentation, returned from tools::Rd_db()
tag

character(1). Desired metadata type.

These types are supported:

  • title.

  • description.

  • usage.

  • arguments.

  • value.

  • references.

  • seealso.

  • examples.

Note

Updated 2020-04-12.

See also

tools::Rd_db().

Examples

db <- tools::Rd_db("base")
head(names(db))

#> [1] "Arithmetic.Rd"   "AsIs.Rd"         "Bessel.Rd"       "CallExternal.Rd"
#> [5] "Colon.Rd"        "Comparison.Rd"  
Rd <- db[["nrow.Rd"]]
class(Rd)

#> [1] "Rd"
summary(Rd)

#>       Length Class  Mode
#>  [1,]  1     -none- list
#>  [2,]  1     -none- list
#>  [3,]  1     -none- list
#>  [4,]  1     -none- list
#>  [5,]  1     -none- list
#>  [6,]  1     -none- list
#>  [7,]  1     -none- list
#>  [8,] 20     -none- list
#>  [9,]  5     -none- list
#> [10,]  4     -none- list
#> [11,] 10     -none- list
#> [12,] 10     -none- list
#> [13,] 11     -none- list
#> [14,] 16     -none- list
RdTags(Rd)

#>  [1] "title"       "name"        "alias"       "alias"       "alias"      
#>  [6] "alias"       "keyword"     "description" "usage"       "arguments"  
#> [11] "value"       "references"  "seealso"     "examples"   
examples <- parseRd(Rd, tag = "examples")
print(examples)

#>  [1] "ma <- matrix(1:12, 3, 4)"                                        
#>  [2] "nrow(ma)   # 3"                                                  
#>  [3] "ncol(ma)   # 4"                                                  
#>  [4] ""                                                                
#>  [5] "ncol(array(1:24, dim = 2:4)) # 3, the second dimension"          
#>  [6] "NCOL(1:12) # 1"                                                  
#>  [7] "NROW(1:12) # 12"                                                 
#>  [8] ""                                                                
#>  [9] "## as.matrix() produces 1-column matrices from 0-length vectors,"
#> [10] "## and so does cbind() :"                                        
#> [11] "dim(as.matrix(numeric())) # 0 1"                                 
#> [12] "dim(    cbind(numeric())) # ditto"                               
#> [13] "## consequently, NCOL(.) gives 1, too :"                         
#> [14] "NCOL(numeric()) # 1 and hence"                                   
#> [15] "NCOL(NULL)      # 1"