dodgr (version 0.4.2)

dodgr_uncontract_graph: Re-expand a contracted graph.

Description

Revert a contracted graph created with dodgr_contract_graph back to a full, uncontracted version. This function is mostly used for the side effect of mapping any new columns inserted on to the contracted graph back on to the original graph, as demonstrated in the example.

Usage

dodgr_uncontract_graph(graph)

Value

A single data.frame representing the equivalent original, uncontracted graph.

Arguments

graph

A contracted graph created from dodgr_contract_graph.

Details

Note that this function will generally not recover original graphs submitted to dodgr_contract_graph. Specifically, the sequence dodgr_contract_graph(graph) |> dodgr_uncontract_graph() will generally produce a graph with fewer edges than the original. This is because graphs may have multiple paths between a given pair of points. Contraction will reduce these to the single path with the shortest weighted distance (or time), and uncontraction will restore only that single edge with shortest weighted distance, and not any original edges which may have had longer weighted distances.

See Also

Other modification: dodgr_components(), dodgr_contract_graph()

Examples

graph0 <- weight_streetnet (hampi)
nrow (graph0) # 6,813
graph1 <- dodgr_contract_graph (graph0)
nrow (graph1) # 760
graph2 <- dodgr_uncontract_graph (graph1)
nrow (graph2) # 6,813

# Insert new data on to the contracted graph and uncontract it:
graph1$new_col <- runif (nrow (graph1))
graph3 <- dodgr_uncontract_graph (graph1)
# graph3 is then the uncontracted graph which includes "new_col" as well
dim (graph0)
dim (graph3)