Tokenize strings by character

Tokenize strings by character in a similar way as the strsplit function in the base package. The function can return a matrix of tokenized items when index is missing. If index is given, tokenized items in the selected position(s) are returned. See examples.

strtoken(x, split, index, ...)

Arguments

x

A vector of character strings; non-character vectors are cast into characters.

split

A character to split the strings.

index

Numeric vector indicating which fields should be returned; if missing or set to NULL, a matrix containing all fields are returned.

...

Other parameters passed to strsplit

Value

A matrix if index is missing, NULL, or contains more than one integer indices; otherwise a character vector.

References

The main body of the function is modified from the strsplit2 function in the limma package.

See also

strsplit

Author

Jitao David Zhang <jitao_david.zhang@roche.com>

Examples

myStr <- c("HSV\t1887", "FCB\t1900", "FCK\t1948")
strsplit(myStr, "\t")
#> [[1]]
#> [1] "HSV"  "1887"
#> 
#> [[2]]
#> [1] "FCB"  "1900"
#> 
#> [[3]]
#> [1] "FCK"  "1948"
#> 

strtoken(myStr, "\t")
#>      [,1]  [,2]  
#> [1,] "HSV" "1887"
#> [2,] "FCB" "1900"
#> [3,] "FCK" "1948"
strtoken(myStr, "\t", index=1L)
#> [1] "HSV" "FCB" "FCK"
strtoken(myStr, "\t", index=2L)
#> [1] "1887" "1900" "1948"

myFac <- factor(myStr)
strtoken(myFac, "\t")
#>      [,1]  [,2]  
#> [1,] "HSV" "1887"
#> [2,] "FCB" "1900"
#> [3,] "FCK" "1948"
strtoken(myFac, "\t", index=1L)
#> [1] "HSV" "FCB" "FCK"