shipunov (version 1.17.1)

Recode: Basic multiple recoding

Description

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

Usage

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

Value

Recoded vector (note that mode will not necessarily be the same, e.g., when recoding numbers with characters).

Arguments

var

Variable to recode

from

'from' column of the recoding "table"

to

'to' column

char

If TRUE (default), do not treat 'to' character vectors as factors

recycle

If TRUE (not default), recycle 'to' along 'from'

missed

Replace missed (not recoded) with something, default is "" (empty charactrer string)

...

Further options to Recode() and RecodeR()

Author

Alexey Shipunov

Details

Basic multiple recoding is similar to 'SQL' left join.

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

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

To understand the idea better, please 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 not recoded (missing). By default, this will replace 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 replace non-RecodeR()'ed entries with empty string ("").

Examples

## 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="")

## Recode4() when value recoded to itself
Recode4(1:5, 1:4, c(2, 1, 3, 3), NA)
Recode4(1:5, 1:4, c(2, 1, 3, 3))

## this is how "char" option works
Recode(1, 1, factor(2), char=FALSE)
Recode(1, 1, factor(2))

## this is how "recycle" option works
Recode(1:3, 1:3, 4)
Recode(1:3, 1:3, 4, recycle=TRUE)