Graphics for description of r.stats.zonal¶

To be run in a GRASS GIS session, North Carolina sample dataset.

Requires d.explanation.plot (GRASS GIS addon), pngquant, optipng and ImageMagic mogrify.

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import os

from IPython.display import Image

import grass.script as gs
import grass.jupyter as gj

gs.set_raise_on_error(True)
gs.set_capture_stderr(True)
os.environ["GRASS_OVERWRITE"] = "1"

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# zoom to spatial subset of "zipcodes" map (5 x 5 pixels)
!g.region n=225430 s=225380 w=640250 e=640300 res=10 -p

# average elevation in zipcode areas
!r.stats.zonal base=zipcodes cover=elevation method=average output=zipcodes_elev_avg
!r.colors zipcodes_elev_avg color=elevation -g

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plot = gj.Map(use_region=True, width=1100, height=1100)
plot.d_background(color="white")
plot.run(
    "d.explanation.plot",
    a="zipcodes",
    b="elevation",
    c="zipcodes_elev_avg",
    label_a="zipcode areas",
    label_b="elevation",
    label_c="Avg elev. / area",
    operator_font="FreeMono:Regular",
)
plot.show()

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filename = "r_stats.zonal.png"
plot.save(filename)
!mogrify -trim {filename}
!pngquant --ext ".png" -f {filename}
!optipng -o7 {filename}
Image(filename)

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