title: Pandas plot dataframe as scatter complains of unknown item
body: <p>I have thousands of data points for two values Tm1 and Tm2 for a series of text lables of type :</p>
  
  <pre><code>    Tm1 Tm2
  ID      
  A01 51  NaN
  A03 51  NaN
  A05 47  52
  A07 47  52
  A09 49  NaN
  </code></pre>
  
  <p>I managed to create a pandas DataFrame with the values from csv. I now want to plot the Tm1 and Tm2 as y values against the text ID's as x values in a scatter plot, with different color dots in pandas/matplotlib.</p>
  
  <p>With a test case like this I can get a line plot</p>
  
  <pre><code>from pandas import *
  df2= DataFrame([52,54,56],index=["A01","A02","A03"],columns=["Tm1"])
  df2["Tm2"] = [None,42,None]
  
  
  Tm1 Tm2
  A01 52  NaN
  A02 54  42
  A03 56  NaN
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/2jMAT.png" alt="Plot obtained from DataFrame"></p>
  
  <p>I want to not connect the individual values with lines and just have the Tm1 and Tm2 values as scatter dots in different colors. </p>
  
  <p>When I try to plot using</p>
  
  <pre><code>df2.reset_index().plot(kind="scatter",x='index',y=["Tm1"])
  </code></pre>
  
  <p>I get an error:</p>
  
  <pre><code>KeyError: u'no item named index'
  </code></pre>
  
  <p>I know this is a very basic plotting command, but am sorry i have no idea on how to achieve this in pandas/matplotlib. The scatter command does need an x and y value but I somehow am missing some key pandas concept in understanding how to do this.</p>