calc_pcareduceres <- function(obj, reduce) {

  if (!reduce) {

    return(t(obj))

  }

  df <- data.frame(x = 1:20)

  df$sdev <- prcomp(t(obj), scale = TRUE)$sdev[1:20]

  optpoint <- which.min(

    vapply(

      2:10,

      function(i) {

        data$x2 <- pmax(0, data$x - i)

        sum(lm(sdev ~ x + x2, df)$residuals^2)

      },

      0

    )

  )

  pcadim <- optpoint + 1

  tmpdata <- t(apply(obj, 1, scale))

  colnames(tmpdata) <- colnames(obj)

  tmppc <- prcomp(t(tmpdata), scale = TRUE)

  return(t(tmpdata) %*% tmppc$rotation[, 1:pcadim])

}