Added methods from_csv and from_dataframe to geodataframe.

from_dataframe takes a pandas dataframe, requires columns that
correspond to x/y, converts to point objects, and then creates a
geodataframe. from_csv simply wraps from_dataframe.

geopandas/geodataframe.py

@@ -9,7 +9,7 @@
 
 import numpy as np
 from pandas import DataFrame, Series
-from shapely.geometry import mapping, shape
+from shapely.geometry import mapping, shape, Point
 from shapely.geometry.base import BaseGeometry
 from six import string_types
 
@@ -197,6 +197,66 @@ def from_features(cls, features, crs=None):
         df.crs = crs
         return df
 
+    @classmethod
+    def from_dataframe(cls, df, xcol, ycol, crs=None):
+        """
+        Alternate constructor to create a GeoDataFrame from a pandas
+        DataFrame in which two columns specify x/y coordinates.
+
+        Parameters
+        ----------
+        df : pandas DataFrame
+        xcol : str
+            Label specifying column name of x coordinate.
+        ycol : str
+            Label specifying column name of y coordinate.
+
+        Returns
+        -------
+        geodataframe : GeoDataFrame
+        """
+
+        if xcol not in df.keys():
+            raise KeyError("%s not found in dataframe" % xcol)
+        if ycol not in df.keys():
+            raise KeyError("%s not found in dataframe" % ycol)
+
+        attr_keys = set(df.keys()).difference(set([xcol, ycol]))
+        points = [dict(geometry=Point(row[xcol], row[ycol]),
+                       **row[attr_keys].to_dict()) for (i, row)
+                       in df.iterrows()]
+        geodf = GeoDataFrame.from_dict(points)
+
+        return geodf
+
+    @classmethod
+    def from_csv(cls, filename, xcol, ycol, crs=None, **kwargs):
+        """
+        Alternate constructor to create a GeoDataFrame from a csv file in
+        which two columns specify x/y coordinates. Wraps from_dataframe method.
+
+        Parameters
+        ----------
+        df : pandas DataFrame
+        xcol : str
+            Label specifying column name of x coordinate.
+        ycol : str
+            Label specifying column name of y coordinate.
+        crs : str (optional)
+            Coordinate system
+
+        Remaining **kwargs are passed to pandas.DataFrame.from_csv
+
+        Returns
+        -------
+        geodataframe : GeoDataFrame
+        """
+
+        df = DataFrame.from_csv(filename, **kwargs)
+        geodf = cls.from_dataframe(df, xcol, ycol, crs=crs)
+
+        return geodf
+
     @classmethod
     def from_postgis(cls, sql, con, geom_col='geom', crs=None, index_col=None,
                      coerce_float=True, params=None):