R/GenHeatMap.R

In conoroheocha/NBSVisTool: Visualisation and mapping for datasets from systematic reviews and maps

#' Create heatmap from dataset
#'
#' Feed in a dataset and get a heatmap in return
#'
#' @param idata Input dataframe
#' @param selcols Numeric vector of column indices
#' @param axis_txt_lim character limit for label text
#'
#' @return Returns a heatmap object showing number of literature under different categories in user specified \code{selcols}
#' @keywords internal
#' @author Ezgi Tanriver-Ayder and Sanita Dhaubanjar

GenHeatMap <- function(idata, selcols, axis_txt_lim = 60) {

  # if df is a shapefile, remove geometry column
  if (any(class(idata) == "sf")) {
    idata <- sf::st_drop_geometry(idata)
  }

  # Bind variables locally to function (helps avoid R CMD notes)
  listone <- listtwo <- n <- NULL

  # Convert columns to factors to allow for categorical classification for both numeric and character data -------
  tmp <- as.data.frame(sapply(idata[selcols], function(x) as.factor(x)))


  # Plot Heatmap ------
  heatmp <- tmp %>%
    dplyr::rename(listone = colnames(tmp[1]), listtwo = colnames(tmp[2])) %>%
    dplyr::count(listone, listtwo) %>%
    tidyr::complete(listone, listtwo, fill = list(n = 0)) %>%
    ggplot2::ggplot(ggplot2::aes(x = listone, y = listtwo, fill = n, label = n)) +
    ggplot2::geom_tile(alpha = 0.3, color = "grey60") +
    ggplot2::geom_text() +
    viridis::scale_fill_viridis() +
    ggplot2::theme_minimal() +
    ggplot2::theme(
      axis.text.x = ggplot2::element_text(angle = 45, hjust = 1),
      panel.grid = ggplot2::element_blank(),
      text = ggplot2::element_text(size = 14),
      axis.title = ggplot2::element_text(size = 16),
      title = ggplot2::element_text(size = 18)
    ) +
    ggplot2::xlab(paste0(selcols[1])) +
    ggplot2::ylab(paste0(selcols[2])) +
    ggplot2::labs(fill = "Count") +
    # Limit axis text to a certain number of characters, so that long text doesn't ruin the chart display
    ggplot2::scale_x_discrete(labels = function(x) substr(x, 1, axis_txt_lim)) +
    ggplot2::scale_y_discrete(labels = function(x) substr(x, 1, axis_txt_lim)) +
    ggplot2::ggtitle("Study Heatmap", subtitle = paste(selcols[2], "by", selcols[1]))

  heatmp
}