title: ConversionError: Failed to convert value(s) to axis units
body: <p>I have a dataframe <code>dd</code> containing 84 rows and 3 columns.</p>
  <p>Now I want to plot an Area Plot with it, and use its index as xticks, so I do the following:</p>
  <pre class="lang-py prettyprint-override"><code>dd.plot(kind='area')
  plt.show()
  </code></pre>
  <p>But I got this result:
  <a href="https://i.stack.imgur.com/RHHp8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RHHp8.png" alt="result" /></a></p>
  <p>(P.S. I dont have enough reputation to post a picture, so I put this link here.)</p>
  <p>It turns out that some xticks are hidden automatically: there should be 84 xticks, but only 9 of them are shown (seems to be hidden automatically).</p>
  <p>I found a similar question <a href="https://stackoverflow.com/questions/27201357/how-to-avoid-some-xticks-are-auto-hidden-in-pandas">here</a>, but when I tried the method mentioned in the link, I got an <code>CnoversionError</code>:</p>
  <pre class="lang-py prettyprint-override"><code>ConversionError: Failed to convert value(s) to axis units: Index(['!', '&quot;', '#', '$', '%', '&amp;', ''', '(', ')', '*', '+', ',', '-', '.',
         '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '&lt;',
         '=', '&gt;', '?', '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
         'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
         'Y', 'Z', '[', '\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f',
         'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't'],
        dtype='object')
  </code></pre>
  <p>I noticed that the difference between my question and the link above is that the index of my DataFrame has a dtype <code>object</code> (they are string), and I found that if I change the index to a list of int, the error does go away.</p>
  <p>The code to reproduce the Error:</p>
  <pre class="lang-py prettyprint-override"><code>import pandas as pd
  import matplotlib.pyplot as plt
  import numpy as np
  
  dd=pd.DataFrame(np.random.rand(84,3),index=[chr(ascii) for ascii in range(33,33+84)])
  
  dd.plot(kind='area',xticks=dd.index)
  
  plt.show()
  </code></pre>
  <p>Thanks for your kindly reply in advance!</p>