title: Converting a column of Polygons from string to GeoPandas geometry
body: <p>I have a dataframe stored as csv file, one column of which is Polygon object. However, this column is stored as strings instead of GeoPandas geometry object. How can I convert this column to Geopandas geometry object so that I can perform geo analysis?</p>
  
  <p>This is how my data looks like</p>
  
  <pre class="lang-py prettyprint-override"><code>my_df['geometry'].head()
  </code></pre>
  
  <pre class="lang-py prettyprint-override"><code>0    POLYGON ((-122.419942 37.809021, -122.419938 3...
  1    POLYGON ((-122.419942 37.809021, -122.419938 3...
  2    POLYGON ((-122.419942 37.809021, -122.419938 3...
  3    POLYGON ((-122.419942 37.809021, -122.419938 3...
  4    POLYGON ((-122.405659 37.806674, -122.405974 3...
  Name: geometry, dtype: object
  </code></pre>
  
  <p>I want to convert this Pandas DataFrame to Geopandas GeoDataFrame, using the column 'geometry' as the Geopandas geometry column.</p>
  
  <pre class="lang-py prettyprint-override"><code>my_geo_df = gpd.GeoDataFrame(my_df, geometry=my_df['geometry'])
  </code></pre>
  
  <p>However, as the column is stored as strings, Geopandas.DataFrame() does not recognize it and therefore cannot actually create a GeoDataFrame.</p>
  
  <pre class="lang-py prettyprint-override"><code>TypeError: Input geometry column must contain valid geometry objects.
  </code></pre>