Hi, wonder if anyone can help me with path and bbox. I have a set of ocean
drifter tracks and I want to know if they pass through a particular boxed
area. This is straightforward to do but I wanted to try to do it with
matplotlib.transforms and matplotlib.path, which look well-suited to this
kind of task using 'intersects_bbox'.
The essence of my code is below. I have a single drifter track (lon, lat)
and have defined a boxed area. At no time does the drifter approach or
enter the box - however, the final line,
print track.intersects_bbox(bbox)
returns True, which it shouldn't. In total I have 340 tracks. My code says
74 pass though the box, but by counting there should be only about 9. Any
help appreciated, thanks, Evan
import numpy as N
import numpy.ma as MA
import matplotlib.transforms as BB
import matplotlib.path as PP
In [200]: lon
Out[200]:
masked_array(data = [-15.52 -15.521 -15.541 ..., -- -- --],
mask = [False False False ..., True True True],
fill_value=1e+20)
In [201]: lat
Out[201]:
masked_array(data = [29.2 29.2 29.196 ..., -- -- --],
mask = [False False False ..., True True True],
fill_value=1e+20)
In [202]: len(lon), len(lat)
Out[202]: (3750, 3750)
track = MA.transpose([lon, lat])
track = PP.Path(track)
bbox = BB.Bbox.from_extents(-15.95, 29.6, -15.9, 29.65)
In [206]: print track.intersects_bbox(bbox)
1
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