cap probabilities with a scalar in kernel_wPB_fast

[kevinushey]

Background

The next Rcpp release (see RcppCore/Rcpp#1513) checks that the operands of a sugar expression, and a vector assigned into a matrix row, column or Range subset, have matching lengths. Previously a longer operand was silently truncated to the length of the left-hand side or target. With that check, FDX fails its CRAN checks with:

Error: sugar operands have different lengths (7 and 8)

In kernel_wPB_fast(), probs has numWeights[i] elements (which is less than numTests for i > 0), but it is capped with pmin(probs, NumericVector(numTests, 1.0)), a vector of length numTests. Old Rcpp read only the first numWeights[i] ones, so results were correct.

Change

Cap with the scalar form pmin(probs, 1.0), which does the same thing for any length.

Testing

R CMD check on the patched package passes against both the current Rcpp branch and released Rcpp 1.1.2.