- Fixes For Lingering Issues
- Mulitlinestring Editing
- Conclusion and Thanks
In our last post mapedit and leaflet.js >
discussed remaining tasks for the
RConsortium funded project
mapedit 0.5.0 fixes
a couple of lingering issues, but primarily focuses on bringing the
Leaflet.pm as an
the original editor in
mapedit provided by
leaflet.extras, is a
wonderful tool but struggles with snapping and those pesky holes that we
commonly face in geospatial tasks. Depending on the task, a user might
prefer to continue using
Leaflet.draw, so we will maintain full
support for both editors. We’ll spend the rest of the post demonstrating
Leaflet.pm excels to help illustrate when you might want to
editor = "leafpm".
At a minimum, to follow along with the rest of this post, please update
mapedit and install the new standalone package
leafpm. While we are
it, we highly recommend updating your other geospatial dependencies.
install.packages(c("sf", "leaflet", "leafpm", "mapview", "mapedit")) # lwgeom is optional but nice when working with holes in leaflet.pm # install.packages("lwgeom")
mapedit now supports holes. Let’s look at a quick example in which we
add, edit, and delete holes.
library(sf) library(leaflet) library(mapview) library(mapedit) library(leafpm) # make a contrived polygon with holes for testing outer1 = matrix(c(0,0,10,0,10,10,0,10,0,0),ncol=2, byrow=TRUE) hole1 = matrix(c(1,1,1,2,2,2,2,1,1,1),ncol=2, byrow=TRUE) hole2 = matrix(c(5,5,5,6,6,6,6,5,5,5),ncol=2, byrow=TRUE) outer2 = matrix(c(11,0,11,1,12,1,12,0,11,0),ncol=2, byrow=TRUE) pts1 = list(outer1, hole1, hole2) pts2 = list(outer2) pl1 = st_sf(geom = st_sfc(st_polygon(pts1))) pl2 = st_sf(geom = st_sfc(st_polygon(pts2))) mpl = st_sf(geom = st_combine(rbind(pl1, pl2)), crs=4326) tst = editFeatures(mpl, editor = "leafpm") # look at our creation mapview(tst)
Please note that right mouse click deletes vertexes. For a more real
mapview has a hole. Try to edit
it with the following code.
library(sf) library(leaflet) library(mapview) library(mapedit) library(leafpm) editFeatures(franconia[5,], editor="leafpm")
Leaflet.pm gives us a very pleasant snapping experience, so if you
want to snap, set
editor = "leafpm" and snap away. Snapping is
particular important when drawing/digitizing features from scratch. Here
is how it looks with the example from above.
Snapping is enabled by default.
Fixes For Lingering Issues
Robin Lovelace discovered that at
leaflet zoom level > 17 we lose coordinate precision. Of course,
this is not good enough, so we will prioritize a fix as discussed in
this leaflet.js pull
request will make this
fix fairly straightforward.
I am happy to report that we have found a solution for the loss of
precision. Please let us know if you discover any remaining problems.
We backed into a solution with
approach fits better with
MULTI* features. As an example, let’s edit
one of the
library(sf) library(leaflet) library(mapview) library(mapedit) library(leafpm) editFeatures(trails[4,], editor="leafpm")
Conclusion and Thanks
As of this post we have reached the end of the extremely generous
RConsortium funding of
Although the funding is over, we still expect to actively maintain and
mapedit. One feature that we had hoped to implement as part of
mapedit toolset was editing of feature attributes. This turned out
to be very ambitious, and unfortunately we were not able to implement a
satisfactory solution for this feature during the funding period. We
plan, however, to develop a solution. Your participation, ideas, and
feedback are as vital as ever, so please continue to engage. Thanks to
all those who have contributed so far and thanks to all open source