R/metalist2.R

In cswells1/MeasInv: Collection of Methods to Detect Dichotomous and Polytomous Differential Item Functioning (DIF)

# Transform a data.frame without anchor information to a list
#' @import purrr
#' @import dplyr
#' @importFrom rlang .data
metalist2 <- function(x) {
  
  # chagne all factor variables into character variables
  x <- purrr::modify_if(x, is.factor, as.character)
  x[, 3] <- toupper(x[, 3])
  
  modelGood <- all(x[,3] %in% c('1PLM', '2PLM', '3PLM', 'DRM', 'GRM', 'GPCM'))
  catsGood <- all(x[,2] >= 1)
  if(!modelGood) stop("At least, one of model is mis-specified. Available models are 1PLM, 2PLM, 3PLM, DRM, GRM, and GPCM")
  if(!catsGood) stop("At least, one of score category is less than 2. Score category should be greater than 1")
  
  # check the maximum of category numbers
  max.cat <- max(x[, 2])
  
  # add par.3 column when there is no par.3 column (just in case that all items are 2PLMs)
  if(ncol(x[, -c(1, 2, 3)]) == 2) {
    x <- data.frame(x, par.3=NA)
  }
  
  # give location numbers to each item
  x$loc <- 1:nrow(x)
  
  # give column names
  colnames(x) <- c("id", "cats", "model", paste0("par.", 1:(ncol(x) - 4)), "loc")
  
  # create an empty list to containl all meta information
  meta <- list()
  
  # when dichotomous items are included in a test
  if(2 %in% x[, 2]) {
    
    drm.df <- x %>%
      dplyr::filter(.data$cats <= 2) %>%
      dplyr::select(.data$id, .data$cats, .data$model, .data$par.1, .data$par.2, .data$par.3, .data$loc) %>%
      dplyr::rename(a="par.1", b="par.2", g="par.3")
    
    # give zero values to NA in the guessing parameter column
    drm.df$g[is.na(drm.df$g)] <- 0
    
    # listrize a dafa.frame
    drm.list <- as.list(drm.df)
    
    # contain the list in the meta list
    meta$drm <- drm.list
    
  }
  
  # when polytomous items are included in a test
  if(max.cat > 2) {
    
    plm.df <- x %>%
      dplyr::filter(.data$cats > 2) %>%
      dplyr::select(.data$id, .data$cats, .data$model, .data$par.1, .data$loc) %>%
      dplyr::rename(a="par.1")
    
    # manipulate step parameters to make them as a list
    d <- x %>%
      dplyr::filter(.data$cats > 2) %>%
      dplyr::select(paste0("par.", 2:max.cat)) %>%
      t() %>%
      data.frame() %>%
      purrr::map(data.frame) %>%
      purrr::map(tidyr::drop_na) %>%
      purrr::map(unlist) %>%
      purrr::map(unname)
    names(d) <- paste0("d", 1:nrow(plm.df))
    
    # listrize a dafa.frame
    plm.list <- as.list(plm.df)
    plm.list <- c(plm.list, d=list(d))
    plm.list <- plm.list[c("id","cats", "model", "a", "d", "loc")]
    
    meta$plm <- plm.list
    
  }
  
  meta
  
}