readshapefile() inconsistencies

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
data-visualization

Research direction

Start by running the provided Basemap example with the linked shapefile and compare readshapefile() behavior for the robin and cyl projections at lon_0=0 and other center longitudes. Trace the readshapefile() entry point and projection-related handling; done means the shapefile renders without wraparound lines or missing geometry when lon_0 changes.

Written by the indexing model from the issue text.

Description

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt

map = Basemap(projection='robin', lat_0=0, lon_0=100)
map.readshapefile('./Paleo_Sturtian_750Ma', 'Paleo_Sturtian_750Mm')
plt.show()

The shapefile I'm using can be downloaded from: my github.

Using the "robin" projection:

  • lon_0=0 everything works fine
  • lon_0 = anything else; causes wrap around problems. Horizontal lines through the plot.
    robin

Using the "cyl" projection:

  • lon_0=0 everything works fine.
  • lon_0 = anything else; No lines through the plot but doesn't plot the right side of the shape file.
    cyl

Is it possible to change the center longitude while plotting a shapefile?

Dominant language
Python
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