The pspline function uses P-splines (Eilers and Marx, Statistical Science, 1981), which are a spline basis using a regular set of knots.
Looking at the code for pspline, which isn't so hard, let dx = (max(x) - min(x))/ nterm where nterm is round(2.5 * desired degrees of freedom) The knots go from min(x) -df*dx to max(x) + df*dx. The default df is 4. Once the knots are known, the bs() function generates the pspline basis for me. Terry T ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.