In r-spatial/mapview: Interactive Viewing of Spatial Data in R

knitr::opts_chunk$set(fig.width = 8.83, message = FALSE)

Despite the possibility to quickly plot spatial data, mapview has a set of arguments for finer control of the visualization. Depending on the object class, these are:

All types

• map - the leaflet or mapview map to use -> default NULL
• col.regions - the color palette for colouring raster, polygon and point areas (points are essentially circles) -> default hcl.colors with palette "Inferno" for raster data and palette "viridis" for vector data
• at - breakpoints used for the colouring -> default NULL meaning they are calculated automatically for the range of data
• na.color - the color for NA values -> default #BEBEBE80
• map.types - the types of the background maps -> default r mapview::mapviewGetOption("basemaps") see here for available map types
• alpha.regions - the opacity of raster, polygon and point fills -> default 0.8 for raster, 0.6 for polygons and 0.9 for points
• legend - whether to add a legend to the plot -> default FALSE
• legend.opacity - opacity of the legend -> default 1
• verbose - whether to print additional information to the console during the rendering -> default FALSE
• layer.name - the layer name to be used for plotting -> default depends on call. For a single object the name of the object; if zcol is supplied a combination of object name and column name; for raster stack/bricks the layer names
• ... - further arguments to be passed on to respective leaflet functions such as addRasterImage or adCircleMarkers

raster only

• maxpixels - the maximum number of pixels to plot -> default 500k. This is used so rendering doesn't take forever. This can also be set with mapviewOptions()
• use.layer.names - whether to use the layer names of raster objects -> default FALSE
• trim - should rasters be trimmed off NA values around the edges -> default TRUE

vector only

• zcol - attribute name(s) or column number(s) in attribute table of the column(s) to be rendered -> default NULL
• burst - whether to show all (TRUE) or only one (FALSE) layer(s) -> default FALSE
• color - color (palette) for lines -> default hcl.colors(n, palette = "viridis")
• alpha - opacity of the lines -> default 0.9
• cex - circle size for point data -> default 6. This can also be used to map circle size to an attribute from the object's attribute table by supplying either column name or number
• lwd - line width -> default 2 for lines and points, 1 for polygons
• label - a character vector of labels to be shown on mouseover -> default feature IDs, if zcol is set the values of zcol
• popup - the popup function to use for the popups -> default popupTable(). See chapter on popups for further options

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Here's a few examples of how selected arguments can be used:

Adjusting color, col.regions & at

Similar to the good old spplot, arguments col.regions and at can be used for finer control of the colouring

library(mapview)
library(raster)

pal = mapviewPalette("mapviewTopoColors")

kili_data <- system.file("extdata", "kiliNDVI.tif", package = "mapview")
kiliNDVI <- stack(kili_data)

mapview(kiliNDVI[[1]], col.regions = pal(100), at = seq(-0.2, 1, 0.2), legend = TRUE)

mapview(breweries, zcol = "founded", at = seq(1400, 2200, 200), legend = TRUE)

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Changing map.types

To use a different background map, use argument map.types

mapview(breweries, map.types = c("Esri.WorldShadedRelief", "OpenStreetMap.DE"), color = "grey40")

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Individual layer.name(s)

To individually label the layer names use argument layer.name

mapview(list(franconia, breweries),
        layer.name = c("Franconian districts", "Franconian breweries"))

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Using burst

burst can be used to plot all layers of an object

mapview(breweries, burst = TRUE)

Note how all layers are shown by default. There is a hidden argument hide which can be used to hide all layers but the first.

mapview(breweries, burst = TRUE, hide = TRUE)

When burst used together with zcol, it will produce one layer for all unique values of zcol.

library(poorman)
library(sf)

breweries %>%
  st_intersection(franconia) %>%
  mapview(zcol = "district", burst = TRUE)

Note that for a column with many values there will likely not be enough space for the layers control - we are working on a solution for this issue.

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Setting point size cex

For point data the circle size can be mapped to one of the attributes (features with NA values will be shown as dots)

mapview(breweries, cex = "number.of.types")

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Adjusting opacity

Opacity of lines and fills (regions) can be adjusted using arguments alpha and alpha.regions

mapview(breweries, alpha = 0)

mapview(franconia, alpha.regions = 0.2, aplha = 1)

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Multiple layers

In addition to easily style maps, mapview also makes it easy to add multiple layers to a (possibly laready existing) map. This can be done either by using + or by supplying a list of objects (or both).

library(plainview)

# mapview + object
mapview(list(franconia, breweries)) + poppendorf[[5]]

# mapview + mapview
mapview(franconia, zcol = "district") + mapview(breweries, zcol = "founded")

library(plainview)

# mapview w list of objects
mapview(list(breweries, franconia),
        zcol = list(NULL, "district"),
        legend = list(TRUE, FALSE),
        homebutton = list(FALSE, TRUE)) + poppendorf[[5]]

m1 = mapview(franconia, zcol = "district", col.regions = c("snow", "grey", "red"))
m1 + breweries

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See chapter 3. mapview options for instructions on how to set some of these styling parameters permanently.

r-spatial/mapview documentation built on April 17, 2024, 6:46 p.m.