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Trim levels to map

Source: R/default_split_funs.R
trim_levels_to_map.Rd

This split function constructor creates a split function which trims levels of a variable to reflect restrictions on the possible combinations of two or more variables which the data is split by (along the same axis) within a layout.

Usage 

trim_levels_to_map(map = NULL)

Arguments

map

data.frame. A data.frame defining allowed combinations of variables. Any combination at the level of this split not present in the map will be removed from the data, both for the variable being split and those present in the data but not associated with this split or any parents of it.

Value

A function that can be used as a split function.

Details

When splitting occurs, the map is subset to the values of all previously performed splits. The levels of the variable being split are then pruned to only those still present within this subset of the map representing the current hierarchical splitting context.

Splitting is then performed via the keep_split_levels() split function.

Each resulting element of the partition is then further trimmed by pruning values of any remaining variables specified in the map to those values allowed under the combination of the previous and current split.

See also

trim_levels_in_group().

Examples 

map <- data.frame(
  LBCAT = c("CHEMISTRY", "CHEMISTRY", "CHEMISTRY", "IMMUNOLOGY"),
  PARAMCD = c("ALT", "CRP", "CRP", "IGA"),
  ANRIND = c("LOW", "LOW", "HIGH", "HIGH"),
  stringsAsFactors = FALSE
)

lyt <- basic_table() %>%
  split_rows_by("LBCAT") %>%
  split_rows_by("PARAMCD", split_fun = trim_levels_to_map(map = map)) %>%
  analyze("ANRIND")
tbl <- build_table(lyt, ex_adlb)