Issue 161: by column with plot_grid

NEWS.md

@@ -4,6 +4,10 @@
   clipping is now configurable.
 - Plot assemblies generated by the patchwork package are now supported
   in `as_grob()`, `ggdraw()`, and `plot_grid()`.
+
+## Minor changes
+
+- `plot_grid()` now accepts `byrow` as an argument to place plots by row or by column onto the plot area.  (@BrianLang, #162).  
 
 # cowplot 1.0.0
 

R/plot_grid.R

@@ -37,6 +37,7 @@
 #' @param scale Individual number or vector of numbers greater than 0. Enables you to scale the size of all or
 #'   select plots. Usually it's preferable to set margins instead of using `scale`, but `scale` can
 #'   sometimes be more powerful.
+#' @param byrow Logical value indicating if the plots should be arrange by row (default) or by column.
 #' @param rows Deprecated. Use \code{nrow}.
 #' @param cols Deprecated. Use \code{ncol}.
 #' @examples
@@ -96,6 +97,13 @@
 #'  align = "v"
 #' )
 #'
+#' # can arrange plots on the grid by column as well as by row.
+#' plot_grid(
+#'  p1, NULL, p2, NULL, p3, NULL,
+#'  ncol = 2,
+#'  byrow = TRUE
+#' )
+#'
 #' # can align top of plotting area as well as bottom
 #' plot_grid(
 #'   p1, p5,
@@ -131,7 +139,7 @@ plot_grid <- function(..., plotlist = NULL, align = c("none", "h", "v", "hv"),
                       label_fontfamily = NULL, label_fontface = "bold", label_colour = NULL,
                       label_x = 0, label_y = 1,
                       hjust = -0.5, vjust = 1.5, scale = 1., greedy = TRUE,
-                      cols = NULL, rows = NULL ) {
+                      byrow = TRUE, cols = NULL, rows = NULL) {
 
   # Make a list from the ... arguments and plotlist
   plots <- c(list(...), plotlist)
@@ -158,8 +166,6 @@ plot_grid <- function(..., plotlist = NULL, align = c("none", "h", "v", "hv"),
     rows <- nrow
   }
 
-  # Align the plots (if specified)
-  grobs <- align_plots(plotlist = plots, align = align, axis = axis, greedy = greedy)
 
   # calculate grid dimensions
   if (is.null(cols) && is.null(rows)){
@@ -171,6 +177,12 @@ plot_grid <- function(..., plotlist = NULL, align = c("none", "h", "v", "hv"),
   if (is.null(cols)) cols <- ceiling(num_plots/rows)
   if (is.null(rows)) rows <- ceiling(num_plots/cols)
 
+  # if the user wants to layout the plots by column, we use the calculated rows to reorder plots
+  if (!byrow) plots <- plots[c(t(matrix(c(1:num_plots, rep(NA, (rows * cols) - num_plots)), nrow = rows, byrow = byrow)))]
+
+  # Align the plots (if specified)
+  grobs <- align_plots(plotlist = plots, align = align, axis = axis, greedy = greedy)
+
   if ("AUTO" %in% labels)
     labels <- LETTERS[1:num_plots]
   else if ("auto" %in% labels)

tests/testthat/test_plot_grid.R

@@ -27,6 +27,10 @@ test_that("basic plot arranging works", {
   expect_doppelganger("scaling plots",
     plot_grid(p1, p2, p3, labels = "AUTO", scale = c(.9, .7, .5), nrow = 1) + theme_map() # add theme_map() for plot title
   )
+
+  expect_doppelganger("colwise arranging",
+    plot_grid(p1, NULL, p2, p3, NULL, byrow = FALSE) + theme_map() # add theme_map() for plot title
+  )
 })