itemCoding {arules} | R Documentation |
Provides the generic functions and the S4 methods for converting item labels into column IDs used in the binary matrix representation and vice versa.
decode
converts from the numeric (column IDs) representation to
readable item labels. decode
is used by LIST
.
encode
converts from readable item labels to an itemMatrix using a
given coding. With this method it is possible to create several compatible
itemMatrix
objects (i.e., use the same binary representation for
items) from data.
recode
recodes an itemMatrix
object so its coding is compatible
with another object or the matrix follows a certain order of items.
decode(x, ...) ## S4 method for signature 'list' decode(x, itemLabels) ## S4 method for signature 'numeric' decode(x, itemLabels) encode(x, ...) ## S4 method for signature 'list' encode(x, itemLabels, itemMatrix = TRUE) ## S4 method for signature 'character' encode(x, itemLabels, itemMatrix = TRUE) ## S4 method for signature 'numeric' encode(x, itemLabels, itemMatrix = TRUE) recode(x, ...) ## S4 method for signature 'itemMatrix' recode(x, itemLabels = NULL, match = NULL)
x |
a vector or a list of vectors of character strings
(for |
itemLabels |
a vector of character strings used for coding where
the position of an item label in the vector gives the item's column ID.
The used |
itemMatrix |
return an object of class |
match |
an |
... |
further arguments. |
recode
always returns an object
of class itemMatrix
.
For encode
with itemMatrix = TRUE
an object
of class itemMatrix
is returned.
Otherwise the result is of the same type as x
, e.g., a
list or a vector.
LIST
,
associations-class
,
itemMatrix-class
data("Adult") ## Example 1: Manual decoding ## get code iLabels <- itemLabels(Adult) head(iLabels) ## get undecoded list and decode in a second step list <- LIST(Adult[1:5], decode = FALSE) list decode(list, itemLabels = iLabels) ## Example 2: Manually create an itemMatrix data <- list( c("income=small", "age=Young"), c("income=large", "age=Middle-aged") ) iM <- encode(data, iLabels) iM inspect(iM) ## use the itemMatrix to create transactions as(iM, "transactions") ## Example 3: use recode ## select first 100 transactions and all education-related items sub <- Adult[1:100, itemInfo(Adult)$variables == "education"] itemLabels(sub) image(sub) ## recode to match Adult again sub.recoded <- recode(sub, match = Adult) image(sub.recoded)