ks905383
Check for CRS on geopandas object
I think it would be nice to have a simple helper function to add a CRS to an input geopandas object that doesn't have one.
import geopandas as gp
import pooch
import xagg as xa
import xarray as xr
# Load in example data and shapefiles
ds = xr.tutorial.open_dataset("air_temperature")
file = pooch.retrieve(
"https://pubs.usgs.gov/of/2006/1187/basemaps/continents/continents.zip", None
)
continents = gp.read_file("zip://" + file)
# Assume this geopandas object does not have a CRS set
continents.crs = None
# Calculate weights
wm = xa.pixel_overlaps(ds, continents)
This returns the following traceback:
ValueError: Must pass either crs or epsg.
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-30-52fa646d6f28> in <module>
----> 1 wm = xa.pixel_overlaps(ds, continents)
~/miniconda3/envs/analysis/lib/python3.8/site-packages/xagg/wrappers.py in pixel_overlaps(ds, gdf_in, weights, weights_target, subset_bbox)
52 # Get overlaps between these pixel polygons and the gdf_in polygons
53 print('calculating overlaps between pixels and output polygons...')
---> 54 wm_out = get_pixel_overlaps(gdf_in,pix_agg)
55 print('success!')
56
~/miniconda3/envs/analysis/lib/python3.8/site-packages/xagg/core.py in get_pixel_overlaps(gdf_in, pix_agg)
249
250 # Match up CRSes
--> 251 pix_agg['gdf_pixels'] = pix_agg['gdf_pixels'].to_crs(gdf_in.crs)
252
253 # Get GeoDataFrame of the overlaps between every pixel and the polygons
~/miniconda3/envs/analysis/lib/python3.8/site-packages/geopandas/geodataframe.py in to_crs(self, crs, epsg, inplace)
814 else:
815 df = self.copy()
--> 816 geom = df.geometry.to_crs(crs=crs, epsg=epsg)
817 df.geometry = geom
818 df.crs = geom.crs
~/miniconda3/envs/analysis/lib/python3.8/site-packages/geopandas/geoseries.py in to_crs(self, crs, epsg)
533 crs = CRS.from_epsg(epsg)
534 else:
--> 535 raise ValueError("Must pass either crs or epsg.")
536
537 # skip if the input CRS and output CRS are the exact same
ValueError: Must pass either crs or epsg.
Maybe this is super obvious, but I was a bit confused by the error message. The pixel_overlap function doesn't allow one to pass in a CRS, so I'd say either:
- Update the error message to say
ValueError: Please add a CRS to your Geopandas object with gdf_in.set_crs("EPSG:4326") - Add a quick line in the function that is something like:
if gdf_in.crs is None:
gdf_in.set_crs("ESPG:4326")
Thanks for that example!
I think personally I'm in favor of just putting in a better error message; xagg probably shouldn't assume a CRS of any input to avoid any odder silent errors. Thoughts?
I'll see about putting this in the next release!
I think personally I'm in favor of just putting in a better error message; xagg probably shouldn't assume a CRS of any input to avoid any odder silent errors. Thoughts?
Yes this is probably a good philosophy and a really easy implementation. I would just offer a suggestion in the error message of how to fix this issue, since it's relatively straight-forward, but might not be for someone newer to working with shapefiles.
great packages!! i have "install" this xagg packages with amount of efforts! however, when i run the example as along (basic function as weightmap = xa.pixel_overlaps(ds,gdf,weights=ds_pop.pop)), i still got this errors "ValueError: Must pass either crs or epsg"! I'm stuck here. I don't know what to do. Any help to a newer ? Thanks very much!
full errors as:
creating polygons for each pixel...
regridding weights to data grid...
/home/miniconda3/envs/cmip_env/lib/python3.8/site-packages/xarray/core/dataarray.py:853: FutureWarning: elementwise
comparison failed; returning scalar instead, but in the future will perform elementwise comparison
return key in self.data
calculating overlaps between pixels and output polygons...
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
Input In [7], in <cell line: 2>()
1 # Calculate overlaps
----> 2 weightmap = xa.pixel_overlaps(ds,gdf,weights=ds_pop.pop)
File ~/miniconda3/envs/cmip_env/lib/python3.8/site-packages/xagg/wrappers.py:84, in pixel_overlaps(ds, gdf_in, weights, weights_target, subset_bbox, impl)
82 # Get overlaps between these pixel polygons and the gdf_in polygons
83 print('calculating overlaps between pixels and output polygons...')
---> 84 wm_out = get_pixel_overlaps(gdf_in,pix_agg,impl=impl)
85 print('success!')
87 return wm_out
File ~/miniconda3/envs/cmip_env/lib/python3.8/site-packages/xagg/core.py:372, in get_pixel_overlaps(gdf_in, pix_agg, impl)
369 gdf_in['poly_idx'] = np.arange(0,len(gdf_in))
371 # Match up CRSes
--> 372 pix_agg['gdf_pixels'] = pix_agg['gdf_pixels'].to_crs(gdf_in.crs)
374 # Get GeoDataFrame of the overlaps between every pixel and the polygons
375 # (using the EASE grid https://nsidc.org/data/ease)
376 if np.all(gdf_in.total_bounds[[1,3]]>0):
377 # If min/max lat are both in NH, use North grid
378 #epsg_set = {'init':'EPSG:6931'} (change to below bc of depreciation of {'init':...} format in geopandas)
File ~/miniconda3/envs/cmip_env/lib/python3.8/site-packages/geopandas/geodataframe.py:1364, in GeoDataFrame.to_crs(self, crs, epsg, inplace)
1362 else:
1363 df = self.copy()
-> 1364 geom = df.geometry.to_crs(crs=crs, epsg=epsg)
1365 df.geometry = geom
1366 if not inplace:
File ~/miniconda3/envs/cmip_env/lib/python3.8/site-packages/geopandas/geoseries.py:1124, in GeoSeries.to_crs(self, crs, epsg)
1047 def to_crs(self, crs=None, epsg=None):
1048 """Returns a ``GeoSeries`` with all geometries transformed to a new
1049 coordinate reference system.
1050
(...)
1121
1122 """
1123 return GeoSeries(
-> 1124 self.values.to_crs(crs=crs, epsg=epsg), index=self.index, name=self.name
1125 )
File ~/miniconda3/envs/cmip_env/lib/python3.8/site-packages/geopandas/array.py:771, in GeometryArray.to_crs(self, crs, epsg)
769 crs = CRS.from_epsg(epsg)
770 else:
--> 771 raise ValueError("Must pass either crs or epsg.")
773 # skip if the input CRS and output CRS are the exact same
774 if self.crs.is_exact_same(crs):
ValueError: Must pass either crs or epsg.
