Variables labels and packed columns"

In labelled: Manipulating Labelled Data

The tidyr allows to group several columns of a tibble into one single df-column, see tidyr::pack(). Such df-column is itself a tibble. It's not currently clear why you would ever want to pack columns since few functions work with this sort of data.

library(tidyr)
d <- iris %>%
  as_tibble() %>%
  pack(
    Sepal = starts_with("Sepal"),
    Petal = starts_with("Petal"),
    .names_sep = "."
  )
str(d)
class(d$Sepal)

Regarding variable labels, you may want to define a label for one sub-column of a df-column, or eventually a label for the df-column itself.

For a sub-column, you could use easily var_label() to define your label.

library(labelled)
var_label(d$Sepal$Length) <- "Length of the sepal"
str(d)

But you cannot use directly var_label() for the df-column.

var_label(d$Petal) <- "wrong label for Petal"
str(d)

As d$Petal is itself a tibble, applying var_label() on it would have an effect on each sub-column. To change a variable label to the df-column itself, you could use label_attribute().

label_attribute(d$Petal) <- "correct label for Petal"
str(d)

On the other hand, set_variable_labels() works differently, as the primary intention of this function is to work on the columns of a tibble.

d <- d %>% set_variable_labels(Sepal = "Label of the Sepal df-column")
str(d)

This is equivalent to:

var_label(d) <- list(Sepal = "Label of the Sepal df-column")
str(d)

To use set_variable_labels() on sub-columns, you should use this syntax:

d$Petal <- d$Petal %>%
  set_variable_labels(
    Length = "Petal length",
    Width = "Petal width"
  )
str(d)

If you want to get the list of variable labels of a tibble, by default var_label() or get_variable_labels() will return the labels of the first level of columns.

d %>% get_variable_labels()

To obtain the list of variable labels for sub-columns, you could use recurse = TRUE:

d %>% get_variable_labels(recurse = TRUE)
d %>%
  get_variable_labels(
    recurse = TRUE,
    null_action = "fill",
    unlist = TRUE
  )

labelled documentation built on July 9, 2023, 7:53 p.m.