include functions for presimplify and toposimplify

[mattijn]

This can now works as follow:

import geopandas
import topojson

Select some data

data = geopandas.read_file(geopandas.datasets.get_path("naturalearth_lowres"))
data = data[
    (data.continent == "South America")
]

Use the presimplify option to set a value to simplify. Presimplify applies simplification on the LineStrings before any computation on the topology has happened.

topojson.Topology(
    data, options={'topology':True, 'presimplify':2}
).to_alt(color='properties.name:N', projection='mercator')

Use toposimplify for applying simplification on the LineStrings after performing of topology computation.

topojson.Topology(
    data, options={'topology':True, 'toposimplify':2}
).to_alt(color='properties.name:N', projection='mercator')

Notes:

• Applying toposimplify in combination with topology: False behave the same as presimplify.
• Currently toposimplify does not work in combination with prequantize.
• A lot of counter cases where too small or too high values are used for the simplifying is not covered, since I have not yet a clear feeling what these values for simplification mean.