recoder: Simple and Handy Recoder

In recoder: A Simple and Flexible Recoder

Description

A flexible function for recoding a variable. It can be used for anything from simple explicit recoding to piecewise-defined transformations.

Usage

recoder(var, recode, other = NULL, na = NA, as.what = NULL)

Arguments

var	var is a variable (vector) being recoded.
recode	recode contains the instructions for how the recoding is done. Each instruction is in the form of condition: newvalue and instrunctions must be separated by semicolons (;).
other	When other=NULL, elements that do not satisfy any of the coditions in the instructions given by recode will by defaul remain unchanger, otherwise they will be changed to other
na	When na=NULL, NA values will not be changed in the vector, otherwise, they will be changed to na.
as.what	if as.what is specified, the final vector is forced to be of the given type. For example, it will be made a factor if as.what= "factor" is specified.

Details

recode contains the instructions for how the recoding is done. Each instruction is in the form of condition: newvalue and instrunctions must be separated by semicolons (;). E.g., 1:2; 2:-1; 3:0 will change all ones to two, twos to negative one, and threes to zero. Instruction can include compound conditions and functions for newvalue expressed in terms of $. For example, "<0:0; >2:4; >=0 & <=2 : $^2" will give zero for all the values below 0, 4 for all the values above 2, and squared values for anything between 0 and 2.

The input can be other types beside numeric. For characters and factors, it is important that the form "old":"new" includes quotations around both the left-hand side and the right-hand side.

When the input is a factor, recoding works as expected, but new levels cannot be assigned. In order to assign new levels, the input vector should be made into something else (e.g., a character) and then the argument as.what could be set to "factor" to get a factor as the end result.

Value

The recoded vector is returned.

Author(s)

Ali Sanaei

See Also

cut, recode

Examples

u = rnorm(1000)
u.2 = recoder(u,'<-2: -2; >2 : 2' ,other = 0)
plot(u,u.2)

# use a function of 'x' for assigning new values based on old values
u.3 = recoder(u,'<-2: -2; >2 : 2; >=-2 & <=2 : $^3/4') 
# NOTE: instructions in recode are executed from left to right
# So u.3 and u.4 are the same
u.4 = recoder(u,'<-2: -2; >=-2 : $^3/4;  >2 : 2')
plot(u, u.3)

# another example of a piecewise defined function
x = runif(1000,-1,10)
y = recoder(x,'>0 & <1: sqrt($); >=1 : 1+log($)' ,other=NA) 
plot(y~x)
table(is.na(y))

# we can also create other types of variables
k = rpois(n = 10000, lambda = 3)
evodd = recoder(k %% 2, '0: "even"; 1: "odd" ')
table(evodd)

# the output could also be made a factor, etc., using "as.what" argument
evodd.factor = recoder(k %% 2, '0: "even"; 1: "odd" ', as.what='factor')

# characters are recoded similarly
str = c('a','b','x','z',NA) 
str2 = recoder(str, '"x":"c"; "z":"d" ')
str3 = recoder(str, '"a":1; "b":2; "x":3; "z":4 ')
print(str3) #note that this is still not numeric
num3 = recoder(str, '"a":1; "b":2; "x":3; "z":4 ', as.what='numeric')
print(num3)

# when input is a factor, the levels are fixed
f1 = factor( c('a','b','x','z',NA)  )
f2 = recoder( f1, '"x":"a"; "z":"b" ')

## Not run: 
f3 = recoder(f1, '"x":"c"; "z":"d" ') # "c" and "d" are not recognized

## End(Not run)
f3 = recoder( as.character(f1), '"x":"c"; "z":"d" ' , as.what= "factor")

Example output

Loading required package: stringr

FALSE  TRUE 
  912    88 
evodd
even  odd 
5087 4913 
[1] "1" "2" "3" "4" NA 
[1]  1  2  3  4 NA
Warning messages:
1: In `[<-.factor`(`*tmp*`, index, value = "c") :
  invalid factor level, NA generated
2: In `[<-.factor`(`*tmp*`, index, value = "d") :
  invalid factor level, NA generated

recoder documentation built on May 2, 2019, 2:42 a.m.