title: How to print a 'null' for any of many values that may have no value
body: <p>I'm running some statistics stuff (example):</p>
  
  <pre><code>Chi_min=str(min(chi))
  Chi_max=str(max(chi))
  Teff_min=str(min(Temp))
  Teff_max=str(max(Temp))
  Tin_min=str(min(Tin))
  Tin_max=str(max(Tin))
  Tau_min=str(min(Tau))
  Tau_max=str(max(Tau))
  Mdots_min=str(min(Mdots))
  Mdots_max=str(max(Mdots))
  Chi_sdev=str(sp.stats.tstd(chi))
  Teff_sdev=str(sp.stats.tstd(Temp))
  Tin_sdev=str(sp.stats.tstd(Tin))
  Tau_sdev=str(sp.stats.tstd(Tau))
  Mdots_sdev=str(sp.stats.tstd(Mdots))
  </code></pre>
  
  <p>and I have the results being printed out onto a single line like so</p>
  
  <pre><code>NewResults=NewResults+str(data[RowStar][0])+'\t'+str(RowStar+1)+'\t'+str(ChiThresh)+'\t'+str(BestX)+'\t'+str(Teff)+'\t'+Teff_min+'\t'+Teff_max+'\t'+Teff_sdev+'\t'+Teff_sdev2+'\t'+Teff_med+'\t'+str(Tempin)+'\t'+Tin_min+'\t'+Tin_max+'\t'+Tin_sdev+'\t'+Tin_med
  </code></pre>
  
  <p>I'm missing a few columns when it writes to the file. I suspect that it's not putting anything down for any null values. What is the easiest way to have python print out a value of 'null' for any value that doesn't have any output?</p>