Reads the raw sc sample, the build-stage complete-case index (`keep_sc`), the covariate matrix `Xc`, and the pseudo-weights from `build`. Remove NA placeholders inserted by `na.exclude` so that all returned vectors and matrices have the same length (the number of build-stage complete cases).
prepare_sc_data(build)A list with components:
- `sc`: data frame of build-stage complete cases. - `X`: covariate matrix `build$internal$Xc`. - `w`: pseudo-weight vector with NA placeholders removed. - `idx_keep`: integer index of which rows of `raw_sc` were retained.
A `pw_fit` object returned by the build step.