catchk

Audit categorical inputs before an analysis

R

catchk(x, ref = NULL, nmin = 5)

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.

Parameters

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.

Returns

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".

Notes

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(factor(c("b", "a", "b"), levels = c("a", "b", "c")), ref = "b")

Generated from the R help page: catchk in the R reference.