title: Iterating through dictionaries - FutureWarning: Value based partial slicing on non-monotonic DatetimeIndexes with non-existing keys is deprecated
body: <p>I am transitioning back into Python after much time in R and I can't remember the best methods for storing multiple participants' time series. Some searching suggested dictionaries are good, but as I am iterating through dictionaries I have received the following warning a few times:
  <code>indexing.py:1069: FutureWarning: Value based partial slicing on non-monotonic DatetimeIndexes with non-existing keys is deprecated and will raise a KeyError in a future Version. return self._getitem_tuple_same_dim(tup)</code></p>
  <p>What I should be doing differently? Thank you so much!</p>
  <p><code>df_motion = </code></p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>datetime</th>
  <th>x</th>
  <th>y</th>
  <th>z</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>2020-07-10 13:49:11.429</td>
  <td>0.213234</td>
  <td>-0.069581</td>
  <td>-10.066122</td>
  </tr>
  <tr>
  <td>2020-07-10 13:49:11.440</td>
  <td>0.219219</td>
  <td>-0.047585</td>
  <td>-10.085126</td>
  </tr>
  <tr>
  <td>2020-07-10 13:49:11.450</td>
  <td>0.319219</td>
  <td>-0.057585</td>
  <td>-10.185357</td>
  </tr>
  </tbody>
  </table>
  </div>
  <pre><code>df_motion_dict[1] = df_motion # and other pandas dataframes of motion signals where the keys are a list with missing numbers, for example 1,3,4,10. 
  audience = {}
  for k,v in df_motion_dict.items():
      df_motion = df_motion_dict[k]
      df_motion = df_motion.loc['2020-07-10 13:55' : '2020-07-10 14:25.5', :]
      if len(df_motion)&gt;0: # remove any dataframes not containing data
          audience[k]=df_motion    
  </code></pre>