R/matchit2exact.R

In itpir/SimTests_DEPRECATED: MatchIt: Nonparametric Preprocessing for Parametric Casual Inference

matchit2exact <- function(treat, X, data, distance, discarded,
                          is.full.mahalanobis, verbose=FALSE, ...) {

  if (verbose) {
    cat("Exact matching... \n")
  }

  n <- length(treat)
  xx <- apply(X, 1, function(x) paste(x, collapse = "\r"))
  xx1 <- xx[treat == 1]
  xx0 <- xx[treat == 0]
  cc <- unique(xx1)
  cc <- cc[cc %in% xx0]
  ncc <- length(cc)

  psclass <- rep(NA, n)
  names(psclass) <- names(treat)
  for (i in 1:ncc) {
    psclass[xx == cc[i]] <- i
  }
  res <- list(subclass = psclass, weights = weights.subclass(psclass, treat))
  class(res) <- c("matchit.exact", "matchit")
  return(res)
}