Description Usage Arguments Details Value Author(s) See Also Examples
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.
1 | add.masking(maskPoly,color)
|
maskPoly |
A masking polygon as described above. |
color |
Colour of the mask. Defaults to white, but for example, sea could be shown as blue. |
Returns no value, but draws a mask on the current graphics device as a side effect
None
Chris Brunsdon
1 2 3 4 5 6 7 8 9 10 | # 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)
# Plot census tract boundaries
plot(tracts,add=TRUE)
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Loading required package: maptools
Loading required package: sp
Checking rgeos availability: TRUE
Loading required package: RColorBrewer
Loading required package: MASS
Loading required package: rgeos
rgeos version: 0.3-23, (SVN revision 546)
GEOS runtime version: 3.4.2-CAPI-1.8.2 r3921
Linking to sp version: 1.2-3
Polygon checking: TRUE
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
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