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Plot quick visualizations of grainscape objects

Source: R/plot.R
plot.Rd

Plot quick visualizations of mpg, grain, and corridor objects.

This function is intended to get a quick look at the state of a grainscape object by rendering what are likely to be the most universally useful visualizations of the spatial data within these objects.

Much more control is available using ggGS() with ggplot() enabling the layering of different different analytical products, and the visualization of node and link attributes.

For high-resolution visualization and the greatest level of control use export() to export spatial objects for cartographic representation in a geographic information system (GIS).

Usage

# S4 method for corridor,ANY
plot(x, y, quick = NULL, print = TRUE, theme = TRUE, ...)

# S4 method for grain,ANY
plot(x, y, quick = NULL, print = TRUE, theme = TRUE, ...)

# S4 method for mpg,ANY
plot(x, y, quick = NULL, print = TRUE, theme = TRUE, ...)

Arguments

x

A grainscape object (corridor, grain, or mpg).

y

Ignored.

quick

If NULL (the default) it will plot the most useful quick visualization for the supplied object type. See below for a description of the available quick plots, and the defaults.

print

Render the ggplot on the default graphics device. Default is TRUE.

theme

Apply grainscape theme and scale aesthetics. Default is TRUE.

...

Additional arguments (not used).

Value

   Invisibly, a `ggplot2` object to which additional `ggplot`
           geoms and adjustments can be applied. Has the side effect of
           rendering the plot, unless `print = FALSE`.

Types of visualization available with the quick parameter

"mpgPerimPlot" gives a a vector rendering of the minimum planar graph with vector links connecting the perimeters of the patches. This doesn't accurately represent the sinuosity of paths of the links between patches but offers a good approximation that renders better at large extents. Default for mpg objects. Not available for other objects.

"mpgPlot" gives a raster-only rendering of the minimum planar graph where patchId are positive integers, and linkId are negative integers showing the shortest paths between patches Only available for mpg objects.

"network" gives a vector rendering of the minimum planar graph or the grains of connectivity network with nodes and links plotted at the patch or polygon centroid locations. Available for mpg and grain objects. Default for grain objects.

"grainPlot" gives a raster and vector rendering of the grains of connectivity network with nodes and links plotted at polygon centroid locations, superimposed over the boundaries of the Voronoi polygons. Can be time consuming on large rasters due to the Voronoi boundary extraction. Only available for grain objects.

"corridorPlot" renders the output of a corridor() analysis. It is the only option available with corridor objects and the default.

See also

ggGS(), export(), corridor, grain, mpg

Author

Alex Chubaty and Paul Galpern

Examples

## Load raster landscape
tiny <- raster::raster(system.file("extdata/tiny.asc", package = "grainscape"))

## Create a resistance surface from a raster using an is-becomes reclassification
tinyCost <- raster::reclassify(tiny, rcl = cbind(c(1, 2, 3, 4), c(1, 5, 10, 12)))
## Produce a patch-based MPG where patches are resistance features=1
tinyPatchMPG <- MPG(cost = tinyCost, patch = tinyCost == 1)
## Extract a representative subset of 5 grains of connectivity
tinyPatchGOC <- GOC(tinyPatchMPG, nThresh = 5)
if (interactive()) {
  library(ggplot2)

  ## MPG and showing simplified links among the perimeters of patches
  plot(tinyPatchMPG)

  ## MPG showing links among the nodes of connected patches
  plot(tinyPatchMPG, quick = "network")

  ## MPG showing the shortest paths between patches actually used to
  ## to calculate link weight values
  plot(tinyPatchMPG, quick = "mpgPlot")

  ## A grain of connectivity network plot with Voronoi boundaries
  plot(grain(tinyPatchGOC, 3), quick = "grainPlot")

  ## Capture plot output for further processing with ggplot
  g <- plot(tinyPatchMPG, print = FALSE, theme = FALSE)
  g <- g + theme_minimal() + ggtitle("Minimum planar graph") +
    theme(plot.title = element_text(size = 20, hjust = 0.5)) +
    theme(legend.position = "none") +
    xlab("Easting") + ylab("Northing")
  g

  ## To change aesthetics it is best to build the plot from scratch
  ## using grainscape::ggGS(). See examples therein.
}