pycno 0.0.2

Python map overlay software to read CNO and CNOB files.

pycno

Python map overlay software to read CNO and CNOB files. This provides a light-weight interface to add overlays to matplotlib plots. For longitude/latitude plots, no additional prerequisites are required. For projections, see "projection support." This allows for pure python installation with supplemental support if desired.

status

Very early development. Useful light weight mapping library, but interface likely to change until stable.

install

pip install https://github.com/barronh/pycno/archive/main.zip

to-do: add to pypi.

example usage

By default, this adds coasts and countries to the current axes. If the current axes has no other data on it, provide the xlim/ylim keywords to define the extents.

import pycno
import matplotlib.pyplot as plt


cno = pycno.cno(xlim=(-180, 180), ylim=(-90, 90))
cno.draw()
plt.savefig('coasts_countries.png')

Use the cnopath keyword to specify another overlay. If you specify a cnopath you don't have, it will automatically be downloaded from the Panoply Overlay website. For example, cno.draw('MWDB_Coasts_NA_1.cnob') will download a high-resolution version of North American coasts, continents, and states.

projection support

pycno.cno supports the pyproj projections. If you provide proj, then overlays will be converted to the projection space and xlim/ylim will need to be provided in projection space. This should work for most projections, but has only been tested with Lambert Conformal Conic and Polar Stereographic. If you test it with another projection, please post a comment under issues and let us know.

import pycno
import pyproj
import matplotlib.pyplot as plt


proj = pyproj.Proj(
  (
    '+proj=stere +lat_0=90 +lat_ts=45 +lon_0=-98 ' +
    '+x_0=10098000 +y_0=10098000 +R=6370000 +to_meter=108000 ' +
    '+no_defs'
  ),
  preserve_units=True
)
plt.axis('image')
cno = pycno.cno(proj=proj, xlim=(0, 187), ylim=(0, 187))
cno.draw()
plt.savefig('coasts_countries_ps.png')