title: fill_between gives "ValueError: Argument dimensions are incompatible"
body: <p>Code below written in Python imports data from Excel to Python, then plots with matplotlib. I'm trying to fill above and below line 80 with different colors using the <code>fill_between</code> function, but it gives</p>
  
  <pre class="lang-none prettyprint-override"><code>ValueError: Argument dimensions are incompatible
  </code></pre>
  
  <p><strong>Note:</strong> the Excel file (<code>'eegg.xlsx'</code>) has 4 columns with 682 rows and contains <code>int</code> data (0-100).</p>
  
  <p>I think the problem is with the <code>where</code> argument of the <code>fill_between</code> calls, but I cannot solve this. </p>
  
  <pre><code>import xlrd
  import numpy
  from datetime import time
  from pylab import *
  
  workbook = xlrd.open_workbook('eegg.xlsx')
  worksheet = workbook.sheet_by_name('Sayfa1')
  num_rows = worksheet.nrows - 1
  num_cells = worksheet.ncols - 1
  curr_row = -1
  
  att=[]
  med=[]
  for i in [2,3]:
      kolon = worksheet.col(i)
      for x in kolon[1:]:
          d= int(x.value)
          if i==2:
              att.append(d)
          elif i==3:
              med.append(d)
  
  n = len(att)
  X = np.linspace(0,n,n,endpoint=True)
  Y1 = att
  plot(X, Y1, color='blue', alpha=1.00)
  fill_between(X, 0, Y1, (Y1) &gt; 80, color='red', alpha=.25)
  fill_between(X, 0, Y1, (Y1) &lt; 80, color='blue', alpha=.25)
  xlim(0,n), xticks([])
  ylim(0,110), yticks([])
  </code></pre>