Use curved() inside dagify() formulas to specify per-edge curvature.
This function should only be used inside dagify() formulas; calling it
directly will result in an error, similar to dplyr::n().
Value
This function is not intended to be called directly. It is detected
in the formula AST by dagify().
Curvature sign convention
Per-edge curvature is drawn by the ggarrow edge engine only. Set it with
edge_engine = "ggarrow" on geom_dag() and the ggdag_*() quick plots, or
globally with ggdag_options_set(edge_engine = "ggarrow"); the default
ggraph engine draws every edge with the curvature of its own edge type
and warns when it is handed a per-edge value it cannot draw.
ggarrow follows the grid::curveGrob() convention, so positive curvature
curves below (to the right of) a left-to-right edge and negative curvature
curves above it. ggdag passes the value through untouched.
A bidirected edge has no direction of its own, so ggdag draws it from the
endpoint dagitty stores first. Naming its endpoints the other way round,
as in curve_edge(dag, "y", "x", 0.5) for an edge stored as x <-> y,
curves the edge to the same side of the page: the sign is flipped to match
the direction the edge is drawn in.
Examples
# Curve the edge from m to y
dagify(
y ~ x + curved(m, 0.5),
m ~ x
)
#> dag {
#> m
#> x
#> y
#> m -> y
#> x -> m
#> x -> y
#> }