Query node coordinates

These functions allow to query specific coordinate values from the geometries of the nodes.

Usage

node_X()

node_Y()

node_Z()

node_M()

Value

A numeric vector of the same length as the number of nodes in the network.

Details

Just as with all query functions in tidygraph, these functions are meant to be called inside tidygraph verbs such as mutate or filter, where the network that is currently being worked on is known and thus not needed as an argument to the function. If you want to use an algorithm outside of the tidygraph framework you can use with_graph to set the context temporarily while the algorithm is being evaluated.

Note

If a requested coordinate value is not available for a node, NA will be returned.

Examples

library(sf, quietly = TRUE)
library(tidygraph, quietly = TRUE)

# Create a network.
net = as_sfnetwork(roxel)

# Use query function in a filter call.
filtered = net |>
  activate(nodes) |>
  filter(node_X() > 7.54)

oldpar = par(no.readonly = TRUE)
par(mar = c(1,1,1,1))
plot(net, col = "grey")
plot(filtered, col = "red", add = TRUE)

par(oldpar)

# Use query function in a mutate call.
net |>
  activate(nodes) |>
  mutate(X = node_X(), Y = node_Y())
#> # A sfnetwork: 987 nodes and 1215 edges
#> #
#> # A directed multigraph with 9 components and spatially explicit edges
#> #
#> # Dimension: XY
#> # Bounding box: xmin: 7.522595 ymin: 51.94151 xmax: 7.546705 ymax: 51.96119
#> # Geodetic CRS: WGS 84
#> #
#> # Node data: 987 × 3 (active)
#>              geometry     X     Y
#>           <POINT [°]> <dbl> <dbl>
#> 1 (7.538109 51.95286)  7.54  52.0
#> 2 (7.537867 51.95282)  7.54  52.0
#> 3 (7.537815 51.95867)  7.54  52.0
#> 4 (7.537015 51.95848)  7.54  52.0
#> 5 (7.533441 51.95578)  7.53  52.0
#> 6 (7.533415 51.95561)  7.53  52.0
#> # ℹ 981 more rows
#> #
#> # Edge data: 1,215 × 5
#>    from    to name               type                                   geometry
#>   <int> <int> <chr>              <chr>                          <LINESTRING [°]>
#> 1     1     2 Hagemanns Kämpken  residential (7.538109 51.95286, 7.537867 51.95…
#> 2     3     4 Stiegkamp          residential (7.537815 51.95867, 7.537015 51.95…
#> 3     5     6 Havixbecker Straße residential (7.533441 51.95578, 7.533467 51.95…
#> # ℹ 1,212 more rows

# Use query function directly.
X = with_graph(net, node_X())
head(X)
#> [1] 7.538109 7.537867 7.537815 7.537015 7.533441 7.533415