recode: Change, rearrange or consolidate the values of an existing or new variable. Inspired by the RECODE command from SPSS.

Description

recode change, rearrange or consolidate the values of an existing variable based on conditions. Design of this function inspired by RECODE from SPSS. Sequence of recodings provided in the form of formulas. For example, 1:2 ~ 1 means that all 1's and 2's will be replaced with 1. Each value will be recoded only once. In the assignment form recode(...) = ... of this function values which doesn't meet any condition remain unchanged. In case of the usual form ... = recode(...) values which doesn't meet any condition will be replaced with NA. One can use values or more sophisticated logical conditions and functions as a condition. There are several special functions for usage as criteria - for details see criteria. Simple common usage looks like: recode(x, 1:2 ~ -1, 3 ~ 0, 1:2 ~ 1, 99 ~ NA). For more information, see details and examples. The ifs function checks whether one or more conditions are met and returns a value that corresponds to the first TRUE condition. ifs can take the place of multiple nested ifelse statements and is much easier to read with multiple conditions. ifs works in the same manner as recode - e. g. with formulas. But conditions should be only logical and it doesn't operate on multicolumn objects.

Usage

recode(
  x,
  ...,
  with_labels = FALSE,
  new_label = c("all", "range", "first", "last")
)
rec(x, ..., with_labels = TRUE, new_label = c("all", "range", "first", "last"))
recode(x, with_labels = FALSE, new_label = c("all", "range", "first", "last")) <- value
rec(x, with_labels = TRUE, new_label = c("all", "range", "first", "last")) <- value
ifs(...)
lo
hi
copy(x)
from_to(from, to)
values %into% names

Value

object of the same form as x with recoded values

Format

An object of class numeric of length 1.

Arguments

x: vector/matrix/data.frame/list
...: sequence of formulas which describe recodings. They are used when from/to arguments are not provided.
with_labels: logical. FALSE by default for 'recode' and TRUE for 'rec'. Should we also recode value labels with the same recodings as variable?
new_label: one of "all", "range", "first", or "last". If we recode value labels ('with_labels = TRUE') how we will combine labels for duplicated values? "all" will use all labels, "range" will use first and last labels. See examples.
value: list with formulas which describe recodings in assignment form of function/to list if from/to notation is used.
from: list of conditions for values which should be recoded (in the same format as LHS of formulas).
to: list of values into which old values should be recoded (in the same format as RHS of formulas).
values: object(-s) which will be assigned to names for %into% operation. %into% supports multivalue assignments. See examples.
names: name(-s) which will be given to values expression. For %into%.

Details

Input conditions - possible values for left-hand side (LHS) of formula or element of from list:

vector/single value All values in x which equal to elements of the vector in LHS will be replaced with RHS.
function Values for which function gives TRUE will be replaced with RHS. There are some special functions for the convenience - see criteria.
single logical value TRUE It means all other unrecoded values (ELSE in SPSS RECODE). All other unrecoded values will be changed to RHS of the formula or appropriate element of to.

Output values - possible values for right-hand side (RHS) of formula or element of to list:

value replace elements of x. This value will be recycled across rows and columns of x.
vector values of this vector will replace values in the corresponding position in rows of x. Vector will be recycled across columns of x.
function This function will be applied to values of x which satisfy recoding condition. There is a special auxiliary function copy which just returns its argument. So, in the recode it just copies old value (COPY in SPSS RECODE). See examples.

%into% tries to mimic SPSS 'INTO'. Values from left-hand side will be assigned to right-hand side. You can use %to% expression in the RHS of %into%. See examples. lo and hi are shortcuts for -Inf and Inf. They can be useful in expressions with %thru%, e. g. 1 %thru% hi.

Examples

Run this code

# examples from SPSS manual
# RECODE V1 TO V3 (0=1) (1=0) (2, 3=-1) (9=9) (ELSE=SYSMIS)
v1  = c(0, 1, 2, 3, 9, 10)
recode(v1) = c(0 ~ 1, 1 ~ 0, 2:3 ~ -1, 9 ~ 9, TRUE ~ NA)
v1

# RECODE QVAR(1 THRU 5=1)(6 THRU 10=2)(11 THRU HI=3)(ELSE=0).
qvar = c(1:20, 97, NA, NA)
recode(qvar, 1 %thru% 5 ~ 1, 6 %thru% 10 ~ 2, 11 %thru% hi ~ 3, TRUE ~ 0)
# the same result
recode(qvar, 1 %thru% 5 ~ 1, 6 %thru% 10 ~ 2, ge(11) ~ 3, TRUE ~ 0)

# RECODE STRNGVAR ('A', 'B', 'C'='A')('D', 'E', 'F'='B')(ELSE=' '). 
strngvar = LETTERS
recode(strngvar, c('A', 'B', 'C') ~ 'A', c('D', 'E', 'F') ~ 'B', TRUE ~ ' ')

# recode in place. Note that we recode only first six letters
recode(strngvar) = c(c('A', 'B', 'C') ~ 'A', c('D', 'E', 'F') ~ 'B')
strngvar

# RECODE AGE (MISSING=9) (18 THRU HI=1) (0 THRU 18=0) INTO VOTER. 
age = c(NA, 2:40, NA)
voter = recode(age, NA ~ 9, 18 %thru% hi ~ 1, 0 %thru% 18 ~ 0)
voter
# the same result with '%into%'
recode(age, NA ~ 9, 18 %thru% hi ~ 1, 0 %thru% 18 ~ 0) %into% voter2
voter2
# recode with adding labels
voter = recode(age, "Refuse to answer" = NA ~ 9, 
                    "Vote" = 18 %thru% hi ~ 1, 
                    "Don't vote" = 0 %thru% 18 ~ 0)
voter

# recoding with labels
ol = c(1:7, 99)
var_lab(ol) = "Liking"
val_lab(ol)  = num_lab("
                     1 Disgusting
                     2 Very Poor
                     3 Poor
                     4 So-so
                     5 Good
                     6 Very good
                     7 Excellent
                     99 Hard to say
                     ")

recode(ol, 1:3 ~ 1, 5:7 ~ 7, TRUE ~ copy, with_labels = TRUE)
# 'rec' is a shortcut for recoding with labels. Same result: 
rec(ol, 1:3 ~ 1, 5:7 ~ 7, TRUE ~ copy)
# another method of combining labels
recode(ol, 1:3 ~ 1, 5:7 ~ 7, TRUE ~ copy, with_labels = TRUE, new_label = "range")
# example with from/to notation
# RECODE QVAR(1 THRU 5=1)(6 THRU 10=2)(11 THRU HI=3)(ELSE=0).
list_from = list(1 %thru% 5, 6 %thru% 10, ge(11), TRUE)
list_to = list(1, 2, 3, 0)
recode(qvar, from_to(list_from, list_to))


list_from = list(NA, 18 %thru% hi, 0 %thru% 18)
list_to = list("Refuse to answer" = 9, "Vote" = 1, "Don't vote" = 0)
voter = recode(age, from_to(list_from, list_to))
voter

# 'ifs' examples
a = 1:5
b = 5:1
ifs(b>3 ~ 1)                       # c(1, 1, NA, NA, NA)
ifs(b>3 ~ 1, TRUE ~ 3)             # c(1, 1, 3, 3, 3)
ifs(b>3 ~ 1, a>4 ~ 7, TRUE ~ 3)    # c(1, 1, 3, 3, 7)
ifs(b>3 ~ a, TRUE ~ 42)            # c(1, 2, 42, 42, 42)

# advanced usage
#' # multiple assignment with '%into%'
set.seed(123)
x1 = runif(30)
x2 = runif(30)
x3 = runif(30)
# note nessesary brackets around RHS of '%into%'
recode(x1 %to% x3, gt(0.5) ~ 1, other ~ 0) %into% (x_rec_1 %to% x_rec_3)
fre(x_rec_1)
# the same operation with characters expansion
i = 1:3
recode(x1 %to% x3, gt(0.5) ~ 1, other ~ 0) %into% text_expand('x_rec2_{i}')
fre(x_rec2_1)

# factor recoding
a = factor(letters[1:4])
recode(a, "a" ~ "z", TRUE ~ copy) # we get factor

# example with function in RHS
data(iris)
new_iris = recode(iris, is.numeric ~ scale, other ~ copy)
str(new_iris)

set.seed(123)
a = rnorm(20)
# if a<(-0.5) we change it to absolute value of a (abs function)
recode(a, lt(-0.5) ~ abs, other ~ copy) 

# the same example with logical criteria
recode(a, when(a<(-.5)) ~ abs, other ~ copy)

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