Geopandas one sided buffer

Question

cs_buffer = cs.copy()
cs_buffer = cs_buffer.to_crs("epsg:25832")
cs_buffer.geometry = cs_buffer.geometry.buffer(40, single_sided=True)
cs_buffer = cs_buffer.to_crs("epsg:4326")

My code should do a single side buffer. The problem is, sometimes it makes the buffer on the wrong side.

I think it is because of the wrong direction of the LINESTRING. As we can see the upper left one is correct. It catches the buildings. The right on is on the wrong side, it should get the upper buildings not the lower ones. Sometimes it is right sometimes it is not.

Is it possible to fix it?

Without Buffer it looks like this

In this example it is also false. Left one is false, right one is correct.

Answer 1

You can decide where the one side buffer should appear, by adding a sign to the distance parameter, as in this brief example:

import geopandas
from shapely.geometry import LineString
import matplotlib.pyplot as plt

s = geopandas.GeoSeries(
    [  
        LineString([(1, 1), (1, 5), (5, 5)])        
    ]
)

fig, ax = plt.subplots()
s.plot(ax=ax, color='red', alpha=0.4)
#plot buffer of s, single side left(up) or right(down)
s.buffer(0.3,single_sided=True).plot(ax=ax, color='green', alpha=0.5)
s.buffer(-0.3,single_sided=True).plot(ax=ax, color='blue', alpha=0.5)
plt.show()

as mentioned in official docs https://shapely.readthedocs.io/en/latest/manual.html#object.buffer