| 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.
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 encode) or of numeric (for decode), or
an object of class itemMatrix (for recode). |
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 itemLabels vector can be obtained from itemMatrix,
transactions and associations by the
method itemLabels. |
itemMatrix |
return an object of class itemMatrix otherwise
an object of the same class as x is returned. |
match |
an itemMatrix object whose item coding x
should match. |
... |
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)