diff --git a/R/mini_plots.R b/R/mini_plots.R
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+#' Helper functions to generate inline sparklines
+#'
+#' @description These functions helps you quickly generate sets of sparkline
+#' style plots using base R plotting system. Currently, we support histogram
+#' and boxplot. You can use them together with `column_spec` to
+#' generate inline plot in tables. By default, this function will save images
+#' in a folder called "kableExtra" and return the address of the file.
+#'
+#' @param x Vector of values or List of vectors of values.
+#' @param width The width of the plot in pixel
+#' @param height The height of the plot in pixel
+#' @param res The resolution of the plot. Default is 300.
+#' @param same_lim T/F. If x is a list of vectors, should all the plots be
+#' plotted in the same range? Default is True.
+#' @param lim Manually specify plotting range in the form of `c(0, 10)`.
+#' @param xaxt On/Off for xaxis text
+#' @param yaxt On/Off for yaxis text
+#' @param ann On/Off for annotations (titles and axis titles)
+#' @param col Color for the fill of the histogram bar/boxplot box.
+#' @param border Color for the border.
+#' @param dir Directory of where the images will be saved.
+#' @param file File name. If not provided, a random name will be used
+#' @param file_type Graphic device. Support `png` or `svg`. SVG is recommended
+#' for HTML output
+#' @param add_label For boxplot. T/F to add labels for min, mean and max.
+#' @param label_digits If T for add_label, rounding digits for the label.
+#' Default is 2.
+#' @param boxlty Boxplot - box boarder type
+#' @param medcol Boxplot - median line color
+#' @param medlwd Boxplot - median line width
+#'
+#' @inheritParams graphics::hist
+#' @inheritParams graphics::boxplot
+#' @export
+spec_hist <- function(x, width = 200, height = 50, res = 300,
+                      breaks = "Sturges",
+                      same_lim = TRUE, lim = NULL,
+                      xaxt = 'n', yaxt = 'n', ann = FALSE,
+                      col = "lightgray", border = NULL,
+                      dir = if (is_latex()) rmd_files_dir() else tempdir(),
+                      file = NULL,
+                      file_type = if (is_latex()) "png" else "svg", ...) {
+  if (is.list(x)) {
+    if (same_lim & is.null(lim)) {
+      lim <- base::range(unlist(x))
+    }
+    return(lapply(x, function(x_) {spec_hist(
+      x = x_, width = width, height = height,
+      breaks = breaks, same_lim = same_lim, lim = lim,
+      xaxt = xaxt, yaxt = yaxt, ann = ann, col = col, border = border,
+      dir = dir, file = file, file_type = file_type, ...
+    )}))
+  }
+
+  if (is.null(lim)) {
+    lim <- base::range(x)
+  }
+
+  file_type <- match.arg(file_type, c("svg", "png"))
+
+  if (!dir.exists(dir)) {
+    dir.create(dir)
+  }
+
+  if (is.null(file)) {
+    file <- tempfile("hist", dir, paste0('.', file_type))
+  }
+
+  if (file_type == "svg") {
+    grDevices::svg(filename = file, width = width / res, height = height / res,
+                   bg = 'transparent')
+  } else {
+    grDevices::png(filename = file, width = width, height = height, res = res,
+                   bg = 'transparent')
+  }
+
+  graphics::par(mar = c(0, 0, 0.2, 0), lwd=0.5)
+  graphics::hist(x, breaks = breaks, xlim = lim, border = border,
+                 xaxt = xaxt, yaxt = yaxt, ann = ann, col = col, ...)
+  grDevices::dev.off()
+
+  if (file_type == "svg") {
+    svg_xml <- xml2::read_xml(file)
+    svg_text <- as.character(svg_xml)
+    unlink(file)
+  } else {
+    svg_text <- NULL
+  }
+  out <- list(path = file, dev = file_type, type = "hist",
+              width = width, height = height, res = res,
+              svg_text = svg_text)
+
+  class(out) <- "kableExtraInlinePlots"
+  return(out)
+}
+
+#' @rdname spec_hist
+#' @export
+spec_boxplot <- function(x, width = 200, height = 50, res = 300,
+                         add_label = FALSE, label_digits = 2,
+                         same_lim = TRUE, lim = NULL,
+                         xaxt = 'n', yaxt = 'n', ann = FALSE,
+                         col = "lightgray", border = NULL,
+                         boxlty = 0, medcol = "red", medlwd = 1,
+                         dir = if (is_latex()) rmd_files_dir() else tempdir(),
+                         file = NULL,
+                         file_type = if (is_latex()) "png" else "svg", ...) {
+  if (is.list(x)) {
+    if (same_lim & is.null(lim)) {
+      lim <- base::range(unlist(x))
+    }
+    return(lapply(x, function(x_) {spec_boxplot(
+      x = x_, width = width, height = height,
+      add_label = add_label, same_lim = same_lim, lim = lim,
+      xaxt = xaxt, yaxt = yaxt, ann = ann,
+      col = col, border = border,
+      boxlty = boxlty, medcol = medcol, medlwd = medlwd,
+      dir = dir, file = file, file_type = file_type, ...
+    )}))
+  }
+
+  if (is.null(lim)) {
+    lim <- base::range(x)
+    lim[1] <- lim[1] - (lim[2] - lim[1]) / 10
+    lim[2] <- (lim[2] - lim[1]) / 10 + lim[2]
+  }
+
+  file_type <- match.arg(file_type, c("svg", "png"))
+
+  if (!dir.exists(dir)) {
+    dir.create(dir)
+  }
+
+  if (is.null(file)) {
+    file <- tempfile("hist", dir, paste0('.', file_type))
+  }
+
+  if (file_type == "svg") {
+    grDevices::svg(filename = file, width = width / res, height = height / res,
+                   bg = 'transparent')
+  } else {
+    grDevices::png(filename = file, width = width, height = height, res = res,
+                   bg = 'transparent')
+  }
+
+  graphics::par(mar = c(0, 0, 0, 0))
+
+  graphics::boxplot(x, horizontal = TRUE, ann = ann, frame = FALSE, bty = 'n', ylim = lim,
+          col = col, border = border,
+          boxlty = boxlty, medcol = medcol, medlwd = medlwd,
+          axes = FALSE, outcex = 0.2, whisklty = 1,
+          ...)
+  if (add_label) {
+    x_median <- round(median(x, na.rm = T), label_digits)
+    x_min <- round(min(x, na.rm = T), label_digits)
+    x_max <- round(max(x, na.rm = T), label_digits)
+    graphics::text(x_median, y = 1.4, labels = x_median, cex = 0.5)
+    graphics::text(x_min, y = 0.6, labels = x_min, cex = 0.5)
+    graphics::text(x_max, y = 0.6, labels = x_max, cex = 0.5)
+  }
+  grDevices::dev.off()
+
+  if (file_type == "svg") {
+    svg_xml <- xml2::read_xml(file)
+    svg_text <- as.character(svg_xml)
+    unlink(file)
+  } else {
+    svg_text <- NULL
+  }
+  out <- list(path = file, dev = file_type, type = "boxplot",
+              width = width, height = height, res = res,
+              svg_text = svg_text)
+  class(out) <- "kableExtraInlinePlots"
+  return(out)
+}
+
+is_latex <- knitr::is_latex_output
+
+rmd_files_dir <- function(create = TRUE) {
+  curr_file_name <- sub("\\.[^\\.]*$", "", knitr::current_input())
+  dir_name <- paste0(curr_file_name, "_files")
+  if (!dir.exists(dir_name) & create) dir.create(dir_name)
+  fig_dir_name <- file.path(dir_name, "figure-latex")
+  if (!dir.exists(fig_dir_name) & create) dir.create(fig_dir_name)
+  return(fig_dir_name)
+}
+