title: Merging geodataframes in geopandas (CRS do not match)
body: <p>I am trying to merge two geodataframes (want to see which polygon each point is in).</p>
  
  <p>The following code gets me a warning first ("<code>CRS does not match!</code>")
  and then an error ("<code>RTreeError: Coordinates must not have minimums more than maximums</code>").</p>
  
  <p>What exactly is wrong in there? Are CRS coordinates systems? If so, why are they not loaded the same way?</p>
  
  <pre><code>import geopandas as gpd
  from shapely.geometry import Point, mapping,shape
  from geopandas import GeoDataFrame, read_file
  #from geopandas.tools import overlay
  from geopandas.tools import sjoin
  
  print('Reading points...')
  points=pd.read_csv(points_csv)
  points['geometry'] = points.apply(lambda z: Point(z.Latitude, z.Longitude), axis=1)
  PointsGeodataframe = gpd.GeoDataFrame(points)
  print PointsGeodataframe.head()
  print('Reading polygons...')
  PolygonsGeodataframe = gpd.GeoDataFrame.from_file(china_shapefile+".shp")
  print PolygonsGeodataframe.head()
  print('Merging GeoDataframes...')
  merged=sjoin(PointsGeodataframe, PolygonsGeodataframe, how='left', op='intersects')
  
  #merged = PointsGeodataframe.merge(PolygonsGeodataframe, left_on='iso_alpha2', right_on='ISO2', how='left')
  print(merged.head(5))
  </code></pre>
  
  <p>Link to data for reproduction:
  <a href="https://www.dropbox.com/sh/7wwmhtfivg4qvjg/AAC0Lr03SYH4XvPJledGpHxma?dl=0" rel="nofollow">Shapefile</a>,
  <a href="https://www.dropbox.com/s/8j8j6uyavi4jdnn/sample_map_data.csv?dl=0" rel="nofollow">GPS points</a></p>