Query sf attributes from the active element of an sfnetwork object
sf_attr(x, name = NULL, active = NULL)sf_attr(x, name, active = NULL) <- value
An object of class sfnetwork.
Name of the attribute to query. If NULL, then all sf
attributes are returned in a list. Defaults to NULL.
Which network element (i.e. nodes or edges) to activate before
extracting. If NULL, it will be set to the current active element of
the given network. Defaults to NULL.
The new value of the attribute, or NULL to remove the
attribute.
For the extractor: a list of attributes if name is NULL,
otherwise the value of the attribute matched, or NULL if no exact match is
found and no or more than one partial match is found.
sf attributes include sf_column (the name of the sf column)
and agr (the attribute-geometry-relationships).