title: why do i get PearsonRConstantInputWarning when using stats.boxcox_normmax?
body: <p>i'm trying to transform my data and lessen the skewness of some features with <code>astats.boxcox_normmax</code> to find the best value for boxcox.</p>
  
  <pre><code>### Transforming with boxcox normmax
  for field in list(all_skewed_features) :
      all_data[field]=boxcox1p(all_data[field],stats.boxcox_normmax(all_data[field]+1))
  </code></pre>
  
  <p>but I get this error:</p>
  
  <pre><code>PearsonRConstantInputWarning:
  An input array is constant; the correlation coefficent is not defined.
  </code></pre>
  
  <p>it's interesting that the first time I run the code I have this error but by running it another time I don't have any error.
  is it right to transform data two times?</p>