apply_by_groups: Apply by groups

In specmine: Metabolomics and Spectral Data Analysis and Mining

Apply by groups

Description

Applies a function to groups defined by a metadata variable.

Usage

apply_by_groups(
  dataset,
  metadata.var,
  fn.to.apply = "mean",
  variables = NULL,
  variable.bounds = NULL
)

Arguments

dataset	Dataset to analyze.
metadata.var	Metadata variable used to define groups.
fn.to.apply	Function to apply.
variables	Variables to include.
variable.bounds	Optional numeric bounds for variables.

Value

A matrix-like object with one row per selected variable and one column per group defined by 'metadata.var'. Each cell contains the result of applying 'fn.to.apply' to the values of that variable within the corresponding group.

Examples

data <- matrix(
  c(1, 2, 3, 4, 5, 6),
  nrow = 2,
  dimnames = list(c("x1", "x2"), c("s1", "s2", "s3"))
)
metadata <- data.frame(
  group = c("control", "control", "case"),
  row.names = c("s1", "s2", "s3")
)
dataset <- list(data = data, metadata = metadata)
apply_by_groups(dataset, "group", mean)

specmine documentation built on Aug. 5, 2026, 5:06 p.m.