node_index: Map cell identifiers to graph node indices

In tulpa: Templated Unified Library for Posterior Approximation in Bayesian Hierarchical Models

Map cell identifiers to graph node indices

Description

Translate a vector of original cell identifiers into the 1-based node indices of a tulpa_adjacency graph, by key (not by row order). Use it to add the node-index column the model's spatial grouping bar needs to the observation data, which typically has many rows per cell and a different row order than the graph.

Usage

node_index(graph, ids)

Arguments

graph	A tulpa_adjacency object from adjacency().
ids	A vector of cell identifiers to look up (matched against graph$ids).

Value

An integer vector the same length as ids, giving each one's node index in graph (NA for identifiers absent from the graph).

See Also

adjacency().

Examples

grid <- expand.grid(x = 1:3, y = 1:3)
grid$cell <- paste0("c", seq_len(nrow(grid)))
g <- adjacency(grid, id = "cell")

obs <- data.frame(cell = c("c5", "c1", "c9"))
obs$cell_idx <- node_index(g, obs$cell)
obs

tulpa documentation built on Oct. 19, 2026, 5:09 p.m.