geopandas bug ?

[Peter Otten]

Xristos Xristoou wrote:

> Τη Σάββατο, 14 Ιανουαρίου 2017 - 4:30:48 μ.μ. UTC+2, ο χρήστης Peter Otten
> έγραψε:
>> Xristos Xristoou wrote:
>> 
>> > Τη Σάββατο, 14 Ιανουαρίου 2017 - 3:43:10 μ.μ. UTC+2, ο χρήστης Peter
>> > Otten έγραψε:
>> >> Xristos Xristoou wrote:
>> >> 
>> >> > i want  to create a simple spatial joing using geopandas but i thing
>> >> > so geopandas has bug ?
>> >> 
>> >> Have you tried the examples on
>> >> <http://geopandas.org/mergingdata.html>? Do they work? If yes, inspect
>> >> your data, does it have the same format?
>> 
>> Looks like you chose to ignore the hard part.
>>  
>> >> > geopandas code :
>> >> > 
>> >> > from geopandas import gpd
>> >> > import geopandas
>> >> > points = geopandas.GeoDataFrame.from_file('points.shp') # or geojson
>> >> > etc polys = geopandas.GeoDataFrame.from_file('polygons.shp')
>> >> > pointInPoly = gpd.sjoin(points, polys, how='left',op='within')
>> >> > 
>> >> > error :
>> >> > 
>> >> > Traceback (most recent call last):
>> >> >   File
>> >> >   "/home/sarantis/testshapely/sumpointsinsidepolygon/testgeo.py",
>> >> >   line 7, in <module>
>> >> >     pointInPoly = gpd.sjoin(points, polys, how='left',op='within')
>> >> >   File
>> >> >   "/usr/local/lib/python2.7/dist-packages/geopandas/tools/sjoin.py",
>> >> >   line 57, in sjoin
>> >> >     r_idx = np.concatenate(idxmatch.values)
>> >> > ValueError: need at least one array to concatenate
>> 
>> >> > any idea why ?
>> >> 
>> >> My crystal ball says that either points or polys is empty ;)
>> > 
>> > is not empty and yes i have two shapefiles from qgis.
>> 
>> Can I download those files somewhere?
>> 
>> > what is the error ?
>> 
>> No idea. Without those files I cannot run your code.
> 
> https://www.dropbox.com/s/2693nfi248z0y9q/files.zip?dl=0 with the
> shapefiles

It looks like there are no intersections in your data.
With the proviso that I've learned about the library only today I think you 
should get an empty result set rather than the ValueError.
Here's a way to reproduce the error (?) with the data provided in the 
project:

import geopandas
from geopandas import gpd

world = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))
cities = gpd.read_file(gpd.datasets.get_path('naturalearth_cities'))
countries = world[['geometry', 'name']]

def find(items, name):
    # didn't find the idomatic way quickly, so
    for index, n in enumerate(items["name"]):
        if n == name:
            return items[index:index+1]
    raise ValueError

berlin = find(cities, "Berlin")
paris = find(cities, "Paris")
germany = find(countries, "Germany")

print(gpd.sjoin(berlin, germany))
print(gpd.sjoin(paris, germany)) # ValueError
             
$ python demo.py
                                        geometry name_left  index_right  \
175  POINT (13.39960276470055 52.52376452225116)    Berlin           41   

    name_right  
175    Germany  

[1 rows x 4 columns]
Traceback (most recent call last):
  File "demo.py", line 20, in <module>
    print(gpd.sjoin(paris, germany)) # ValueError
  File "/home/peter/virt/geopandas/lib/python3.4/site-
packages/geopandas/tools/sjoin.py", line 57, in sjoin
    r_idx = np.concatenate(idxmatch.values)
ValueError: need at least one array to concatenate
$

I suggest that you file a bug report.