add.masking: Draw a mask around a Grid Based Image

In GISTools: Further Capabilities in Geographic Information Science

Draw a mask around a Grid Based Image

Description

Takes an ‘mask’ type polygon object - basically a rectangle with a polygon hole cut through it - and draws this over an image. This has the effect of only showing the image inside the hole. This is useful for plotting surfaces defined over a study area, but masking the values outside of the area.

Usage

add.masking(maskPoly,color)

Arguments

maskPoly	A masking polygon of a “Spatial” or “sf” class as described above.
color	Colour of the mask. Defaults to white, but for example, sea could be shown as blue.

Details

Returns no value, but draws a mask on the current graphics device as a side effect

Value

None

Author(s)

Chris Brunsdon, Binbin Lu

See Also

poly.outer, kde.points.

Examples

  
# Data for New Haven to use in example
data(newhaven)
# Do the KDE
breach.dens = kde.points(breach,lims=tracts)
# Plot the result
level.plot(breach.dens)
# Block out the part outside the study area
masker = poly.outer(breach.dens,tracts,extend=100); add.masking(masker)
add.masking(masker,"blue")
  

GISTools documentation built on Oct. 3, 2024, 1:08 a.m.