mapview - interactive viewing of spatial data in R

(CC-BY-SA)

This document was produced on So 19 Mär 2017 using mapview version 1.2.49

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This online documentation to mapview provides the following chapters:

1. mapview basics
2. advanced controls
3. options
4. popups
5. sync & latticeView
6. viewRGB
7. cubeView
8. slideView

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Introduction

mapview is an R package created to help researchers during their spatial data analysis workflow. It provides functions to very quickly and conveniently create interactive visualisations of spatial data.

mapview was created o fill the gap of quick (not presentation grade) interactive plotting to examine and visually investigate spatial data. So far, one had to either:

• (sp)plot the data in R and then toggle back and forth between the static plots (I use RStudio) or
• save the data to the disk and then open in QGIS or similar to interactively examine the results.

The main workhorse function is mapview() and is currently defined for:

• sf objects (POINTS, LINES, POLYGONS and their MULTI flavors),
• sp objects (Points, Lines, Polygons and their DataFrame versions),
• raster objects (Layer, Stack, Brick), SpatialGridDataFrame and SpatialPixelsDataFrame,
• satellite objects

mapview is in large parts based on RStudios leaflet package (think of it as a data-driven leaflet), though in order to aid general spatial analysis workflow, we have added a few special functions.

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General design

A call to mapview() will return an object of class mapview. This class has 2 slots:

• @object - a list of the objects that are displayed on the map. This means that this slot will contain the re-projected (and in the case of Raster* objects possibly re-sampled) objects which enables tracing of the modifications that took place.
• @map - the leaflet map. This is an S3 class object (see leaflet package documentation for details on the specifics).

By default mapView() provides five base layers between which one can toggle (a preview of leaflet layers can be found here):

• CartoDB.Positron (the default active layer)
• CartoDB.DarkMatter
• OpenStreetMap
• Esri.WorldImagery
• OpenTopoMap

Whenever mapview detects that the colors to be rendered are too light (i.e. have a high mean luminence) the default map will be changed from CartoDB.Positron to CartoDB.DarkMatter.

Furthermore, mapview provides the following standard features:

• a mouse coordinates strip giving information about the current mouse position and zoom level.
• a scale bar
• labels when hovering over a feature
• zoom-to-layer buttons (home buttons)
• popups showing feature attributes (if present)

Depending on the object and/or argument settings one or several layers are created (each with or without it’s own legend) that can also be toggled.

Note that in order to render properly, mapview will re-project data for you on the fly to ensure that it will be located correctly on the map which may take some time for larger data sets. If you want to make sure your data is projected so that mapview doesn’t need to re-project it for you, make sure that

• raster data is projected in web mercator (EPSG 3857), i.e. +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs
• vector data is provided in geographic coordinates (EPSG 4326), i.e. +proj=longlat +datum=WGS84 +no_defs

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Here’s what a basic call to mapview() will look like

library("mapview")
mapview(breweries)

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For a more detailed introduction to the basic features of mapview see the next chapter on mapview basics

mapview also provides some advanced functionality tailored towards aiding spatial analysis beyond mapping. See the respective chapters for further details.

HAPPY MAPPING!

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