lt_spanner: Add a Column Spanner

In lt: Lightweight Tables via JSON Specs and JavaScript

Add a Column Spanner

Description

A spanner is a label rendered above a contiguous group of column headers.

Usage

lt_spanner(x, label, columns, sep = "[._]")

Arguments

x	An lt() object.
label	A character scalar — the spanner text. Alternatively, a two-sided formula Label ~ col1 + col2 providing both the label (LHS) and columns (RHS). When missing, spanners are inferred from column names.
columns	Column names (character or formula). When missing, inferred from column names.
sep	Separator pattern for auto-inference (default "[._]").

Details

When called with no label or columns, infers spanners from column names by splitting on the first . or ⁠_⁠ separator. Contiguous columns sharing a prefix are grouped under that prefix, and column labels are shortened to the suffix.

Value

x with the spanner recorded.

Note

The columns must be contiguous in the body of the table.

Examples

tbl = lt(head(iris))
# Explicit spanner
tbl |> lt_spanner(Sepal ~ Sepal.Length + Sepal.Width)
# Auto-infer from column names
tbl |> lt_spanner()
# raw HTML label (wrap in I())
tbl |> lt_spanner(I("<em>Sepal</em>"), ~ Sepal.Length + Sepal.Width)

lt documentation built on July 10, 2026, 1:09 a.m.