title: Boolean filter geopandas dataframe following shapely within
body: <p>I have a geopandas dataframe I perform a convexhull operation on a multipoint dataset using shapely.</p>
  <pre><code>top_sample_col.within(cvh_base)
  </code></pre>
  <p>This returns a boolean, how do I assign to a new gdf only those that are assigned true? (option A)</p>
  <p>I can use <code>.set_index()</code> but then how do I filter by the index=True (option B)</p>
  <p>Option A is the preferred method.</p>
  <p>Edit</p>
  <p>This does the job, but can it be more streamlined?</p>
  <pre><code>df['within'] = top_sample_col.within(cvh_base)
  df = df.loc[df['within'] == True]
  </code></pre>