substrDBCS {lazy.tools}

R Documentation

Substr Using Column Location as the Unit.

Description

Substr Using Column Location as the Unit.

Usage

substrDBCS(x, start, stop = max(nchar(x, type = "byte")))

Arguments

x	A string vector
start	The first location
stop	The last location

Details

This is for strictly DUOBLE byte characters. NOT for UTF-8 characters. For strictly double byte characters, this is faster than susbtr2.

About rawToChar and charToRaw functions:
To get the raw expression of a string, use
raw <- charToRaw(paste(c(0:9," ",letters,LETTERS),collapse=""))
To get the numeric equivalent of a raw (vector), use
num <- as.numeric(raw) .
To recover the original string, use
char <- rawToChar( as.raw(num) ) .

If the n-th byte is the beginning or the ending location of
a double byte character, substrDBCS(x,n,n) is invalid.
Consult is.DBCS(x) and use with caution.

Value

A vector consisting of the substrings of the input vector.

Examples

# The exa,ple below causes error on R 4.2.0 and above.
## Not run: 
# A string consisting of single and double byte characters
nza <- c(97,98,130,131,100,101,130,134,130,135,104)
za <- rawToChar(as.raw(nza))
Print(za)
# location of the double byte characters
is.DBCS(za)
# The first to the fourth characters
substr(za,1,4)
# The characters stored in the first to the fourth bytes of za.
substrDBCS(za,1,4)

## End(Not run)

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