code: def readCovariatesFile(fFile):
      
      reading in covariate file
  
      cfile   file containing the fixed effects as NxP matrix
              (N=number of samples, P=number of covariates)
      """
      assert os.path.exists(fFile), '%s is missing.'%fFile
      F = SP.loadtxt(fFile)
      if F.ndim==1: F=F[:,SP.newaxis]
      return F
docs: reading in covariate file
  
      cfile   file containing the fixed effects as NxP matrix
              (N=number of samples, P=number of covariates)