title: Scatter plot form dataframe with index on x-axis
body: <p>I've got pandas <code>DataFrame</code>, <code>df</code>, with <code>index</code> named <code>date</code> and the columns <code>columnA</code>, <code>columnB</code> and <code>columnC</code></p>
  
  <p>I am trying to scatter plot <code>index</code> on a x-axis and <code>columnA</code> on a y-axis using the <code>DataFrame</code> syntax.</p>
  
  <p>When I try:</p>
  
  <pre><code>df.plot(kind='scatter', x='date', y='columnA')
  </code></pre>
  
  <p>I ma getting an error <code>KeyError: 'date'</code> probably because the <code>date</code> is not column</p>
  
  <pre><code>df.plot(kind='scatter', y='columnA')
  </code></pre>
  
  <p>I am getting an error:</p>
  
  <pre class="lang-none prettyprint-override"><code>ValueError: scatter requires and x and y column
  </code></pre>
  
  <p>so no default index on x-axis.</p>
  
  <pre><code>df.plot(kind='scatter', x=df.index, y='columnA')
  </code></pre>
  
  <p>I am getting error </p>
  
  <pre class="lang-none prettyprint-override"><code>KeyError: "DatetimeIndex(['1818-01-01', '1818-01-02', '1818-01-03', '1818-01-04',\n
                            '1818-01-05', '1818-01-06', '1818-01-07', '1818-01-08',\n
                            '1818-01-09', '1818-01-10',\n               ...\n  
                            '2018-03-22', '2018-03-23', '2018-03-24', '2018-03-25',\n
                            '2018-03-26', '2018-03-27', '2018-03-28', '2018-03-29',\n 
                            '2018-03-30', '2018-03-31'],\n  
  dtype='datetime64[ns]', name='date', length=73139, freq=None) not in index"
  </code></pre>
  
  <hr>
  
  <p>I can plot it if I use <code>matplotlib.pyplot</code> directly</p>
  
  <pre><code>plt.scatter(df.index, df['columnA'])
  </code></pre>
  
  <p><strong>Is there a way to plot index as <code>x-axis</code> using the <code>DataFrame</code> <code>kind</code> syntax?</strong></p>