title: the pairplot data is not plotting correctly
body: <p>Question:
  I have this code and it gives me an error:  </p>
  
  <blockquote>
    <p>AttributeError: 'NoneType' object has no attribute 'update'  </p>
  </blockquote>
  
  <p>Any suggestions? 
  Thank you so much!</p>
  
  <pre><code>import seaborn as sns
  features = ['rdeep','dtc','rhob', 'gr','npss']
  feature_vectors=df[features]
  
  feature_vectors = feature_vectors.apply(np.nan_to_num)
  feature_vectors.reset_index(inplace=True, drop=True)
  feature_vectors
  sns.pairplot(feature_vectors, dropna=True )
  </code></pre>
  
  <p>Here is the fullstack. Does this help? </p>
  
  <blockquote>
  <pre><code>AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-59-bf2539b2257e&gt; in &lt;module&gt;
        6 feature_vectors.reset_index(inplace=True, drop=True)
        7 feature_vectors
  ----&gt; 8 sns.pairplot(feature_vectors, dropna=True )
  
  c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\seaborn\axisgrid.py
  </code></pre>
    
    <p>in pairplot(data, hue, hue_order, palette, vars, x_vars, y_vars, kind,
    diag_kind, markers, height, aspect, dropna, plot_kws, diag_kws,
    grid_kws, size)
           2105     if grid.square_grid:
           2106         if diag_kind == "hist":
        -> 2107             grid.map_diag(plt.hist, **diag_kws)
           2108         elif diag_kind == "kde":
           2109             diag_kws.setdefault("shade", True)</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\seaborn\axisgrid.py
  </code></pre>
    
    <p>in map_diag(self, func, **kwargs)
           1397                     color = fixed_color
           1398 
        -> 1399                 func(data_k, label=label_k, color=color, **kwargs)
           1400 
           1401             self._clean_axis(ax)</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\pyplot.py
  </code></pre>
    
    <p>in hist(x, bins, range, density, weights, cumulative, bottom,
    histtype, align, orientation, rwidth, log, color, label, stacked,
    normed, data, **kwargs)
           2659         align=align, orientation=orientation, rwidth=rwidth, log=log,
           2660         color=color, label=label, stacked=stacked, normed=normed,
        -> 2661         **({"data": data} if data is not None else {}), **kwargs)
           2662 
           2663 </p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\__init__.py
  </code></pre>
    
    <p>in inner(ax, data, *args, **kwargs)
           1808                         "the Matplotlib list!)" % (label_namer, func.<strong>name</strong>),
           1809                         RuntimeWarning, stacklevel=2)
        -> 1810             return func(ax, *args, **kwargs)
           1811 
           1812         inner.<strong>doc</strong> = _add_data_doc(inner.<strong>doc</strong>,</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\axes\_axes.py
  </code></pre>
    
    <p>in hist(self, x, bins, range, density, weights, cumulative, bottom,
    histtype, align, orientation, rwidth, log, color, label, stacked,
    normed, **kwargs)
           6533         # Unit conversion is done individually on each dataset
           6534         self._process_unit_info(xdata=x[0], kwargs=kwargs)
        -> 6535         x = [self.convert_xunits(xi) for xi in x]
           6536 
           6537         if bin_range is not None:</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\axes\_axes.py
  </code></pre>
    
    <p>in (.0)
           6533         # Unit conversion is done individually on each dataset
           6534         self._process_unit_info(xdata=x[0], kwargs=kwargs)
        -> 6535         x = [self.convert_xunits(xi) for xi in x]
           6536 
           6537         if bin_range is not None:</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\artist.py
  </code></pre>
    
    <p>in convert_xunits(self, x)
            184         if ax is None or ax.xaxis is None:
            185             return x
        --> 186         return ax.xaxis.convert_units(x)
            187 
            188     def convert_yunits(self, y):</p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\axis.py
  </code></pre>
    
    <p>in convert_units(self, x)
           1528             return x
           1529 
        -> 1530         ret = self.converter.convert(x, self.units, self)
           1531         return ret
           1532 </p>
  
  <pre><code>c:\program files\extensions\subpy_1.0.0.0\mc\lib\site-packages\matplotlib\category.py
  </code></pre>
    
    <p>in convert(value, unit, axis)
             51 
             52         # force an update so it also does type checking
        ---> 53         unit.update(values)
             54 
             55         str2idx = np.vectorize(unit._mapping.<strong>getitem</strong>,</p>
  
  <pre><code>AttributeError: 'NoneType' object has no attribute 'update'
  </code></pre>
  </blockquote>