title: Why does float() fail to convert my string to a float?
body: <p>My program is giving me an error when it tries to convert a string from a list of strings to a floating point number. The list is read from a line in a CSV text file and then separated into a list. How do I make this work and why is it going wrong? Here are the relevant bits of code:</p>
  
  <pre><code>def Main():
      srcf = open(bkp, 'r')
      for line in srcf:
          liLn = line.split(',')
  </code></pre>
  
  <p>...Then the following function is called...</p>
  
  <pre><code>def Pred_PSME(liLn):
      dbh = float(liLn[6])
  </code></pre>
  
  <p>Here is the line from the file:</p>
  
  <p><code>1345327,20486,"ABCO","Abies concolor","Y","Y","31.496","0.0779","19.3567",,"0.5602","0",1,"0.9268","11.8968","2.6832","6.6646","2399.256",54.47,24.15,248.47,42.19,9.16,8.16,9.23,272.27,264.11,369.30,345.15,71.80,0.00,0.00,4393.57,4106.22,3239.25,3142.07,854.30,0.00,0.00,,12.70,10.16,15.24,0.02,0.04,0.38,0.38,0.00,0.00,1.95,1.83,1.44,1.40</code></p>
  
  <p>I get this error message:  </p>
  
  <pre><code>Traceback (most recent call last):  
    File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 263, in &lt;module&gt;  
      Main()  
    File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 36, in Main  
      li_tBQI = BQI_Calc(liLn)  
    File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 63, in BQI_Calc  
      di_eqns = {"PSME": Pred_PSME(liLn), "ABAM":Pred_ABAM(liLn), \  
    File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 172, in Pred_PSME  
      dbh = float(liLn[6])  
  ValueError: could not convert string to float: "31.496"
  </code></pre>
  
  <p>I'm using Python 2.7 on an Ubuntu Linux computer.</p>