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rclasstidyversetibbler-haven

How to extract just one of classes of object with multiple classes

Say I have a tibble named `a'. It has three classes:

class(a)

"tbl_df"     "tbl"        "data.frame"

How can I extract just one of these classes?

a$data.frame

does not work.

Another example is a haven_labelled object, b which has three classes:

class(b)
"haven_labelled" "vctrs_vctr"     "double"

How can I extract just the double part of b?

Solution

  • class() results in an unnamed character vector, which you usually subset using numeric indeces x[i], e.g. class(b)[3] to obtain double".

    However you could apply string matching, and write an own my_class() function which is based on a vector of valid class definitions.

    valid <- c("data.frame", "double", "character")

my_class <- function(x) {k <- class(x);k[k %in% valid]}

my_class(a)
# [1] "data.frame"

my_class(b)
# [1] "double"

    Data:

    a <- tibble::as_tibble(data.frame())
b <- haven::labelled()