by-subset function

Finds subsets of a dataframe which is split by variables in a formula.

A data frame is split by a formula into groups. Then subsets are found within each group, and the result is collected into a data frame.

subset_by(data, formula, subset, select, drop = FALSE, join = TRUE, ...)

subsetBy(
  formula,
  subset,
  data = parent.frame(),
  select,
  drop = FALSE,
  join = TRUE,
  ...
)

Arguments

• data: A data frame.
• formula: A right hand sided formula or a character vector of variables to split by.
• subset: logical expression indicating elements or rows to keep: missing values are taken as false.
• select: expression, indicating columns to select from a data frame.
• drop: passed on to [ indexing operator.
• join: If FALSE the result is a list of data frames (as defined by 'formula'); if TRUE one data frame is returned.
• ...: further arguments to be passed to or from other methods.

Returns

A data frame.

Examples

data(dietox)
subsetBy(~Evit, Weight < mean(Weight), data=dietox)

See Also

splitBy, split_by

Author(s)

Søren Højsgaard, sorenh@math.aau.dk