`recode`

substitutes old values of a factor or a numeric
vector by new ones, just like the recoding facilities in some
commercial statistical packages.

1 2 3 4 5 6 |

`x` |
An object |

`...` |
One or more assignment expressions, each
of the form Each In case of the method for If the |

`otherwise` |
a character string or some other value
that the result may obtain. If equal to |

`recode`

relies on the lazy evaluation mechanism of *R*:
Arguments are not evaluated until required by the function they are given to.
`recode`

does not cause arguments that appear in `...`

to be evaluated.
Instead, `recode`

parses the `...`

arguments. Therefore, although
expressions like `1 <- 1:4`

would cause an error action, if evaluated
at any place elsewhere in *R*, they will not cause an error action,
if given to `recode`

as an argument. However, a call of the
form `recode(x,1=1:4)`

, would be a syntax error.

If John Fox' package "car" is installed, `recode`

will also be callable
with the syntax of the `recode`

function of that package.

A numerical vector, factor or an `item`

object.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | ```
x <- as.item(sample(1:6,20,replace=TRUE),
labels=c( a=1,
b=2,
c=3,
d=4,
e=5,
f=6))
print(x)
# A recoded version of x is returned
# containing the values 1, 2, 3, which are
# labelled as "A", "B", "C".
recode(x,
A = 1 <- range(min,2),
B = 2 <- 3:4,
C = 3 <- range(5,max), # this last comma is ignored
)
# This causes an error action: the sets
# of original values overlap.
try(recode(x,
A = 1 <- range(min,2),
B = 2 <- 2:4,
C = 3 <- range(5,max)
))
recode(x,
A = 1 <- range(min,2),
B = 2 <- 3:4,
C = 3 <- range(5,6),
D = 4 <- 7
)
# This results in an all-missing vector:
recode(x,
D = 4 <- 7,
E = 5 <- 8
)
f <- as.factor(x)
x <- as.integer(x)
recode(x,
1 <- range(min,2),
2 <- 3:4,
3 <- range(5,max)
)
# This causes another error action:
# the third argument is an invalid
# expression for a recoding.
try(recode(x,
1 <- range(min,2),
3:4,
3 <- range(5,max)
))
# The new values are character strings,
# therefore a factor is returned.
recode(x,
"a" <- range(min,2),
"b" <- 3:4,
"c" <- range(5,6)
)
recode(x,
1 <- 1:3,
2 <- 4:6
)
recode(x,
4 <- 7,
5 <- 8,
otherwise = "copy"
)
recode(f,
"A" <- c("a","b"),
"B" <- c("c","d"),
otherwise="copy"
)
recode(f,
"A" <- c("a","b"),
"B" <- c("c","d"),
otherwise="C"
)
recode(f,
"A" <- c("a","b"),
"B" <- c("c","d")
)
``` |

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