title: TypeError: 'float' object has no attribute '__getitem__' when using reportLab
body: <p>I know that there are loads of questions with the same name, but I couldn't find a question with the same point of problem.
  I am using reportLab for creating a chart, and want to save a drawing to the file, but get the error stated above.
  Here is what I have:</p>
  
  <pre><code>from reportlab.graphics.shapes import Drawing
  from reportlab.graphics.charts.barcharts import VerticalBarChart
  from reportlab.graphics import renderPDF
  
  class Charts:
      def __init__(self):
          self.d = Drawing(300, 200)
  
  
      def drawChart(self, list1, list2):
          chart = VerticalBarChart()
          chart.width = 260
          chart.height = 160
          chart.x = 20
          chart.y = 20
          chart.data = list2
          chart.categoryAxis.categoryNames = list1
          chart.valueAxis.valueMin = 0
          self.d.add(chart)
          renderPDF.drawToFile(self.d, 'example1.pdf', 'My First Drawing')
  </code></pre>
  
  <p>and the error statement is quite long, so this is the end of it:</p>
  
  <pre><code> File "/usr/lib/python2.7/dist-packages/reportlab/graphics/charts/axes.py", line 49, in _findMinMaxValue
  if isinstance(V[0][0],_SequenceTypes):
  TypeError: 'float' object has no attribute '__getitem__'
  </code></pre>
  
  <p>Thanks in advance!</p>