.plotGrob: Plot spatial grobs (using `grid` package)

Description

Internal function. Plot a raster Grob, a points Grob, polygon Grob.

Usage

.plotGrob(grobToPlot, col = NULL, real = FALSE, size = unit(5, "points"),
  minv, maxv, legend = TRUE, legendText = NULL, length = NULL,
  gp = gpar(), gpText = gpar(), pch = 19, speedup = 1, ...)
## S3 method for class 'matrix':
.plotGrob(grobToPlot, col = NULL, real = FALSE,
  size = unit(5, "points"), minv, maxv, legend = TRUE, legendText = NULL,
  length = NULL, gp = gpar(), gpText = gpar(), pch = 19, speedup = 1,
  ...)
## S3 method for class 'SpatialPoints':
.plotGrob(grobToPlot, col = NULL, real = FALSE,
  size = unit(5, "points"), minv, maxv, legend = TRUE, legendText = NULL,
  length = NULL, gp = gpar(), gpText = gpar(), pch = 19, speedup = 1,
  ...)
## S3 method for class 'SpatialPolygons':
.plotGrob(grobToPlot, col = NULL, real = FALSE,
  size = unit(5, "points"), minv, maxv, legend = TRUE, legendText = NULL,
  length = NULL, gp = gpar(), gpText = gpar(), pch = 19, speedup = 1,
  ...)
## S3 method for class 'SpatialLines':
.plotGrob(grobToPlot, col = NULL, real = FALSE,
  size = unit(5, "points"), minv, maxv, legend = TRUE, legendText = NULL,
  length = NULL, gp = gpar(), gpText = gpar(), pch = 19, speedup = 1,
  ...)

Arguments

grobToPlot

Raster*, SpatialLines*, SpatialPoints*, or SpatialPolygons* object.

col

Currently only used for the legend of a Raster* object.

real

Logical indicating whether the data are real numbers (i.e., as opposed to integer or factor).

size

The size of the SpatialPoints.

minv

The minimum value on a Raster*. Required because not all Rasters have this defined internally.

maxv

The maximum value on a Raster*. Required because not all Rasters have this defined internally.

legend

Logical indicating whether a legend should be drawn. Default TRUE.

legendText

Vector of values to use for legend value labels. Defaults to NULL which results in a pretty numeric representation. If Raster* has a Raster Attribute Table (rat; see raster package), this will be used by default. Cur

length

Numeric.

grid parameters, usually the output of a call to gpar.

gpText

gpar object for legend label text.

pch

Point character for SpatialPoints, as par.

speedup

Numeric. The factor by which the number of vertices in SpatialPolygons and SpatialLines* will be subsampled. The vertices are already subsampled by default to make plotting faster.

...

Additional arguments. None currently implemented.

Details

speedup is only used for SpatialPolygons, SpatialPoints, and SpatialLines in this function. Attempts have been made to subsample at a good level that optimizes speed of plotting, without losing visible quality. Nevertheless, to force all points to be plotted, use a speedup value less than 0.1. From a speed perspective, there appears to be an optimal subsampling when using thin from the fastshp package. Presumably, too much thinning requires large distance matrices to be calculated, slowing plotting down. Too little thinning causes an overabundance of points to be plotted, slowing plotting down.

The suggested package fastshp can be installed with: install.packages("fastshp", repos = "http://rforge.net", type = "source").

NOTE: you may get errors relating to not having installed the software tools required for building R packages on your system. For building on Windows, you'll need to install Rtools from https://cran.r-project.org/bin/windows/Rtools/.