mapedit and leaflet.js > 1.0

• Install/Update
• Feature Attribute Editing
• Geojson Precision
• Mulitlinestring Editing
• Crosstalk Integration
• Shiny async
• Conclusion and Thanks

[view raw Rmd]

Back in September 2016, leaflet.js went 1.0 (see Meet Leaflet 1) with a massive changelog from 0.7.0 released three years earlier. Meanwhile, the Leaflet R ecosystem had grown to be very powerful, but also extremely interwoven and quite complex with significant efforts from Joe Cheng and the RStudio team on leaflet core, Bhaskar Karambelkar on leaflet.extras, Tim Appelhans on mapview, and many other open source contributors. Upgrading Leaflet R to leaflet.js > 1.0 would prove to be a massive undertaking. The mapedit team devoted some RConsortium hours to launching the effort, but the entire effort proved well beyond the scope of this initial contribution. Fortunately for the R geospatial community, RStudio very generously provided Barret Schloerke to complete the daunting remaining tasks.

On May 10, 2018, Barret posted Leaflet 2.0.0 on the RStudio blog with not only an upgrade to leaflet.js > 1.0 but also a full upgrade to all leaflet.extras dependencies and very important infrastructure improvements including a test suite to more easily keep up with a quicker leaflet.js release cadence.

mapedit is entirely dependent on Leaflet, so we postponed activity on mapedit until the new Leaflet R release. We are pleased to announce that mapedit is entirely compatible with the new Leaflet and even more pleased to get back to work implementing new features and tackling issues.

In this post, we will highlight the next steps for mapedit in order of priority:

1. feature attribute editing

2. geojson precision

3. multiline string editing

4. crosstalk integration

5. shiny async integration.

We cannot stress enough that the success of achieving these depends greatly on feedback and ideas from the geospatial community, so we highly encourage participation at issues.

Install/Update

As mentioned a lot has changed recently, so we recommend updating leaflet, leaflet.extras, mapview, and mapedit. The newest sf is not required, but while we are at it, we should probably update it also.

install.packages(c("sf", "leaflet", "leaflet.extras", "mapview", "mapedit"))

Feature Attribute Editing

mapedit launched with three objectives:

1. drawing, editing, and deleting features,

2. selecting and querying of features and map regions,

3. editing attributes.

So far, mapedit has focused on 1 and 2 with only a very quick proof of concept shown in mapedit Intro: Ediiting Attributes building on top of geojson.io from Tom Macwright.

Rather than build on top of geojson.io, we would like to tightly integrate attribute editing into mapedit. We will track progress on this issue and would love your participation.

Geojson Precision

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 issue. Hopefully, this leaflet.js pull request will make this fix fairly straightforward.

Mulitlinestring Editing

Leaflet.js and multilinestrings don’t get along as Tim Appelhans reported in issue. For complete support of sf, mapedit should work with multilinestring, so we have promoted this to issue 62.

Crosstalk Integration

Mike Treglia tweeted an interesting use case for mapedit with crosstalk.

want to make interactive scatterplot and map (#GIS) in #rstats – ideally where hovering over point/polygon in map highlights corresponding one in scatterplot, & vice-versa. Favorite examples w/ code? thinking of leaflet/plotly/crosstalk probably, but open to alternatives

— Mike Treglia (@MikeTreglia) December 9, 2017

We welcomed the challenge and responded with this example crosstalking mapedit/leaflet with Plotly and DT.

While the example mostly works, there is far too high a burden on the user. We will try to reduce this down to a couple of lines of code. Issue 72 will track our progress. mapedit will remain targeted toward Shiny contexts, so this effort will focus on crosstalk with Shiny. This plumbing for crosstalk in mapedit should provide a foundation for things like polygon selection in leaflet without Shiny.

Shiny async

RStudio added async support in Shiny as described in the post Shiny 1.1.0: Scaling Shiny with async and webinar Scaling Shiny apps with async programming. No promises here, but async would be very nice for mapedit.

Conclusion and Thanks

As we progress towards these goals, we will post on r-spatial.org, and we would love your help.. mapedit and many of its dependency packages are funded by the RConsortium. Thanks so much to all those who have contributed to this fantastic organization. Also, thanks to all those open source contributors in the R community.