shipunov (version 1.2)

Recode: Basic multiple recoding (similar to 'SQL' left join)

Description

Basic multiple recoding (similar to 'SQL' left join)

Usage

Recode(var, from, to, char=TRUE)
Recode4(var, from, to, missed="")
RecodeR(var, from, to, char=TRUE)
Recode4R(var, from, to, missed="")

Arguments

var

Variable to recode

from

'from' column of the recoding table

to

'to' column

char

If TRUE, do not treat character vectors as factors

missed

Replace missed with something, default is ""

Value

Recoded vector

Details

Recode Basic multiple recoding are similar to 'SQL' left join.

Inspired from Paul Johnston (Univ. of Kansas) recode() function.

Alternatives are car::recode(), lessR::Recode() and 'mgsub' package. First two are much more complicated, third is much slower and less flexible.

To understand the idea better, look on the examples.

There are four functions:

1. Recode() -- base function. If starting points ("from") are the same, only the last rule ("from-to" pair) has an effect. If rules are chained, they still work independently (i.e., chaining has no effect).

2. Recode4() -- considers missing. By default, this will change non-Recode()'d entries with empty string ("").

3. RecodeR() -- running recode. If starting points ("from") are the same, only the first rule ("from-to" pair) has an effect. Chaining is possible.

4. Recode4R() -- running plus considers missing. By default, this will change non-RecodeR()'ed entries with empty string ("").

Examples

# NOT RUN {
## recoding a phrase
phrase <- "The quick brown fox jumps over 123 lazy dogs"
var <- unlist(strsplit(phrase, split=""))
from <- letters[1:20]
to <- rev(from)
Recode.result <- paste(Recode(var, from, to), collapse="")
Recode4.result <- paste(Recode4(var, from, to, missed="-"), collapse="")
RecodeR.result <- paste(RecodeR(var, from, to), collapse="")
Recode4R.result <- paste(Recode4R(var, from, to, missed="-"), collapse="")
from.rule <- paste(from, collapse=" ")
to.rule <- paste(to, collapse=" ")
rbind(from.rule, to.rule, phrase, Recode.result, Recode4.result, RecodeR.result, Recode4R.result)

## reverse complement of DNA sequence
dna <- "GAATTC" # EcoR1 palindromic sequence
paste(Recode(rev(strsplit(dna, NULL)[[1]]),
 c("A", "T", "G", "C"), c("T", "A", "C", "G")), collapse="") # = 'dna', as expected
dna <- "ATTCGGC" # something random
paste(Recode(rev(strsplit(dna, NULL)[[1]]),
 c("A", "T", "G", "C"), c("T", "A", "C", "G")), collapse="")
# }