ba_layout: Compute a layered layout for a bass-ackwards diagram

In ackwards: Bass-Ackwards Hierarchical Structural Analysis

Compute a layered layout for a bass-ackwards diagram

Description

Returns tidy node coordinates and the edge table needed to render a bass-ackwards diagram. The layout uses a two-pass barycenter algorithm:

Usage

ba_layout(x, min_sep = 1)

Arguments

x	An ackwards object.
min_sep	Minimum horizontal separation between adjacent nodes at the same level. Default 1.0. Increase for wider diagrams.

Details

1. Top-down pass – determines the left-to-right order of factors at each level. Each factor's ordinal rank is the |r|-weighted mean of its parents' ranks in the level above, so siblings that share a parent are grouped together.

2. Bottom-up pass – assigns actual x coordinates. The deepest level (level k) is spread evenly; every upper-level factor is placed at the simple mean x of its primary children: a factor with one primary child lands directly above it; a factor with two primary children lands exactly halfway between them. Falls back to |r|-weighted mean of all children for factors with no primary children. Spreading resolves any remaining overlaps.

After both passes the layout is shifted so that the single level-1 node is always at x = 0.

Value

A list with two data frames:

nodes	One row per factor: id, level, x, y, label. y = -level so level 1 is at the top.
edges	The tidy edge table from x$edges$tidy.

See Also

autoplot.ackwards(), tidy.ackwards()

Examples

x <- ackwards(sim16, k_max = 5)
lay <- ba_layout(x)
head(lay$nodes)

ackwards documentation built on July 25, 2026, 1:08 a.m.