title: Iterating through DataFrame using pandas for stocks
body: <p>I am relatively new to python and <code>pandas</code>. 
  I have a <code>DataFrame</code> with a few stocks and their associated 'low' prices for the past few days. I am trying to iterate through each stock (right now I only have 3 but will eventually have thousands) and then for each stock, I want to see if the current day's 'low' price is greater than yesterday's low price AND I want to see if yesterday's low price is less than the low price from 2 days ago. For each stock that meets this criteria, I eventually want to export them to a csv file. </p>
  
  <pre><code>list = ['IBM', 'AMZN', 'FB'] 
  
  stockData = DataReader(list,  'yahoo', datetime(2016,06,8), datetime.today().utcnow())
  
  low = stockData['Low']
  
  low0 = low.iloc[-1]
  low1 = low.iloc[-2]
  low2 = low.iloc[-3]
  </code></pre>
  
  <p>The variables low0, low1, and low2 are probably not necessary but I do like how they splice out the specific data I want. </p>
  
  <p>I then tried iterating over each stock in my list with my function:</p>
  
  <pre><code>for stock in list:
      if low0 &gt; low1 and low1 &lt; low2:
          print True
      else: 
          print False
  </code></pre>
  
  <p>This is the error I get:
  ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().</p>
  
  <p>I would appreciate any input.</p>