items
Survey Items
Objects of class item
are data vectors with additional information
attached to them like ``value labels'' and ``user-defined missing values''
known from software packages like SPSS or Stata.
The class item
is intended to facilitate data management of
survey data. Objects in this class should not directly used
in data analysis. Instead they should changed into "ordinary" vectors
or factors before. For this see the documentation for as.vector,item-method
.
- Keywords
- manip
Usage
## The constructor for objects of class "item"
## more convenient than new("item",...)
# S4 method for numeric
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)
# S4 method for character
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)# S4 method for logical
as.item(x,…)
# x is first coerced to integer,
# arguments in ... are then passed to the "numeric"
# method.
# S4 method for factor
as.item(x,…)
# S4 method for ordered
as.item(x,…)
# S4 method for POSIXct
as.item(x,…)
# S4 method for double.item
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)
# S4 method for integer.item
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)
# S4 method for character.item
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)
# S4 method for datetime.item
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), …
)
Arguments
- x
for
as.item
methods, any atomic vector; for theunique
,summary
,str
,print
,[
, and<-
methods, a vector with classlabelled
.- labels
a named vector of the same mode as
x
.- missing.values
either a vector of the same mode as
x
, or a list with components"values"
, vector of the same mode asx
(which defines individual missing values) and"range"
a matrix with two rows with the same mode asx
(which defines a range of missing values), or an object of class"missing.values"
.- valid.values
either a vector of the same mode as
x
, defining those values ofx
that are to be considered as valid, or an object of class"valid.values"
.- valid.range
either a vector of the same mode as
x
and length 2, defining a range of valid values ofx
, or an object of class"valid.range"
.- value.filter
an object of class
"value.filter"
, that is, of classes"missing.values"
,"valid.values"
, or"valid.range"
.- measurement
level of measurement; one of "nominal", "ordinal", "interval", or "ratio".
- annotation
a named character vector, or an object of class
"annotation"
- …
further arguments, ignored.
See Also
Examples
# NOT RUN {
x <- as.item(rep(1:5,4),
labels=c(
"First" = 1,
"Second" = 2,
"Third" = 3,
"Fourth" = 4,
"Don't know" = 5
),
missing.values=5,
annotation = c(
description="test"
))
str(x)
summary(x)
as.numeric(x)
test <- as.item(rep(1:6,2),labels=structure(1:6,
names=letters[1:6]))
test
test == 1
test != 1
test == "a"
test != "a"
test == c("a","z")
test != c("a","z")
test
# }
# NOT RUN {
<!-- %in% 1:3 -->
# }
# NOT RUN {
test
# }
# NOT RUN {
<!-- %in% c("a","c") -->
# }
# NOT RUN {
codebook(test)
Test <- as.item(rep(letters[1:6],2),
labels=structure(letters[1:6],
names=LETTERS[1:6]))
Test
Test == "a"
Test != "a"
Test == "A"
Test != "A"
Test == c("a","z")
Test != c("a","z")
Test
# }
# NOT RUN {
<!-- %in% c("A","C") -->
# }
# NOT RUN {
Test
# }
# NOT RUN {
<!-- %in% c("a","c") -->
# }
# NOT RUN {
as.factor(test)
as.factor(Test)
as.numeric(test)
as.character(test)
as.character(Test)
as.data.frame(test)[[1]]
# }