Reports, for each variable, what the functions of this package would
make of it: its storage type, its levels and their counts, missing
values, unused levels, levels counted fewer than nmin times, labels
that differ only by case or white space, a 0/1 or logical coding,
integer codes that look like categories, value labels (as haven makes)
that do not match the values, and which level a default would take as
the reference, and why. Nothing is changed.
Arguments
- x
A vector, a data frame, or a list of vectors (each one a variable, named by its name or position).
- ref
NULL, or the reference level the analysis intends: one level for every variable, or levels named by variable (a named vector or list). Matched exactly to the levels as text; a factor by its label.- nmin
Levels counted fewer times (but at least once) are reported as low: one whole number from 1.
Value
An object of class catchk, a list: ok (TRUE when no
variable has a problem), nmin, vars, a data frame with one row per
variable, and levels, one row per level. vars: var, type, n
(values), nna (missing), nlev (levels), unused (levels never
seen), low (levels seen fewer than nmin times), twin (levels
with a label that differs from another only by case or white space),
bin (logical or 0/1), codes (whole numbers, not 0/1, with at most
10 distinct values: likely category codes), nolab (values seen with
no value label), dlab (value labels shared by two values), ref (the
default reference, NA for none), why, want (the stated
reference), state ("default": the stated level is the default;
"other": present, but must be passed explicitly; "low", "empty"
(never seen), "case" (present only up to case or white space),
"absent"; NA when none is stated) and ok. nlev, unused,
low and twin are NA for a variable that is not categorical.
levels: var, level, label (the value label, NA where none),
n, low, twin (the level it differs from only by case or white
space, NA where none) and ref (TRUE for the default reference).
A variable has a problem when it has missing values, unused or low
levels, twins, value labels, likely codes, fewer than two levels seen,
or a stated reference in state "low", "empty", "case" or
"absent".
Details
Levels are those of a factor, in level order; FALSE and TRUE for a
logical, and 0 and 1 for numbers that are all 0 or 1, both always
listed; otherwise the distinct values as text, in order of first
appearance, and for a labelled vector then the labelled values that do
not occur. Doubles that are not all whole numbers, dates, times, lists
and matrices are not categorical: they are reported with their type and
missing values only.
The default reference: FALSE for a logical and 0 for 0/1 numbers
(sntbnd() takes TRUE and 1 as the treatment), the first level of a
factor (ref = 1 on a table of it), and none otherwise: character
values and codes have no order the package uses, so the reference must
be stated, and a labelled vector is refused until it is decoded.
Labels are compared after trimming white space, making each run of it
one space and ASCII letters lower case; other letters are compared as
they are.
Examples
d <- data.frame(sex = c("Male", "male", "Female", "Female", NA),
custody = c(TRUE, FALSE, TRUE, TRUE, FALSE),
court = c(1L, 2L, 2L, 3L, 1L))
catchk(d, nmin = 2)
#> catchk: 3 variables, 2 with problems
#> var type nlev ref why
#> sex character 3 <NA> no order: state it
#> custody logical 2 FALSE logical: TRUE is the treatment
#> court integer 3 <NA> no order: state it
#> sex: 1 missing; seen fewer than 2 times: "Male", "male"; differ only by case or spaces: "Male", "male"
#> court: seen fewer than 2 times: "3"; numbers that look like category codes
catchk(factor(c("b", "a", "b"), levels = c("a", "b", "c")), ref = "b")
#> catchk: 1 variable, 1 with problems
#> var type nlev ref why
#> x factor 3 a factor: the first level
#> x: never seen: "c"; seen fewer than 5 times: "a", "b"; reference "b": seen fewer than nmin times