spatial_node_predicates | R Documentation |
These functions allow to interpret spatial relations between nodes and
other geospatial features directly inside filter
and mutate
calls. All functions return a logical
vector of the same length as the number of nodes in the network. Element i
in that vector is TRUE
whenever any(predicate(x[i], y[j]))
is
TRUE
. Hence, in the case of using node_intersects
, element i
in the returned vector is TRUE
when node i intersects with any of
the features given in y.
node_intersects(y, ...)
node_is_disjoint(y, ...)
node_touches(y, ...)
node_is_within(y, ...)
node_equals(y, ...)
node_is_covered_by(y, ...)
node_is_within_distance(y, ...)
y |
The geospatial features to test the nodes against, either as an
object of class |
... |
Arguments passed on to the corresponding spatial predicate
function of sf. See |
See geos_binary_pred
for details on each spatial
predicate. 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.
A logical vector of the same length as the number of nodes in the network.
Note that node_is_within_distance
is a wrapper around the
st_is_within_distance
predicate from sf. Hence, it is based on
'as-the-crow-flies' distance, and not on distances over the network. For
distances over the network, use node_distance_to
with edge lengths as weights argument.
library(sf, quietly = TRUE)
library(tidygraph, quietly = TRUE)
# Create a network.
net = as_sfnetwork(roxel) %>%
st_transform(3035)
# Create a geometry to test against.
p1 = st_point(c(4151358, 3208045))
p2 = st_point(c(4151340, 3207520))
p3 = st_point(c(4151756, 3207506))
p4 = st_point(c(4151774, 3208031))
poly = st_multipoint(c(p1, p2, p3, p4)) %>%
st_cast('POLYGON') %>%
st_sfc(crs = 3035)
# Use predicate query function in a filter call.
within = net %>%
activate("nodes") %>%
filter(node_is_within(poly))
disjoint = net %>%
activate("nodes") %>%
filter(node_is_disjoint(poly))
oldpar = par(no.readonly = TRUE)
par(mar = c(1,1,1,1))
plot(net)
plot(within, col = "red", add = TRUE)
plot(disjoint, col = "blue", add = TRUE)
par(oldpar)
# Use predicate query function in a mutate call.
net %>%
activate("nodes") %>%
mutate(within = node_is_within(poly)) %>%
select(within)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.