Implement facet_wrap_paginate() wrapper and n_pages() fix

.gitignore

@@ -7,3 +7,4 @@ src/*.o
 src/*.so
 src/*.dll
 inst/doc
+._*

DESCRIPTION

@@ -15,7 +15,7 @@ BugReports: https://github.com/thomasp85/ggforce/issues
 License: GPL (>=2)
 LazyData: TRUE
 Depends:
-    ggplot2 (>= 2.2.0),
+    ggplot2 (>= 2.2.1.9000),
     R (>= 3.3.0)
 Imports:
     Rcpp (>= 0.12.2),
@@ -41,7 +41,7 @@ Suggests:
     devtools,
     reshape2
 VignetteBuilder: knitr
-Collate:
+Collate: 
     'RcppExports.R'
     'aaa.R'
     'shape.R'
@@ -58,6 +58,7 @@ Collate:
     'facet_stereo.R'
     'facet_wrap_paginate.R'
     'facet_zoom.R'
+    'gen_all_pages_fwp.R'
     'ggforce_package.R'
     'ggproto-classes.R'
     'interpolate.R'

NAMESPACE

@@ -53,6 +53,7 @@ export(facet_stereo)
 export(facet_wrap_paginate)
 export(facet_zoom)
 export(gather_set_data)
+export(gen_all_pages_fwp)
 export(geom_arc)
 export(geom_arc0)
 export(geom_arc2)

R/facet_wrap_paginate.R

@@ -154,7 +154,11 @@ FacetWrapPaginate <- ggproto("FacetWrapPaginate", FacetWrap,
 #' n_pages(p)
 #'
 n_pages <- function(plot) {
-    page <- ggplot_build(plot)$layout$panel_layout$page
+    if (utils::packageVersion('ggplot2') <= '2.2.1') {
+      page <- ggplot_build(plot)$layout$panel_layout$page
+    } else {
+      page <- ggplot_build(plot)$layout$layout$page
+    }
     if (!is.null(page)) {
         max(page)
     } else {

R/gen_all_pages_fwp.R

@@ -0,0 +1,29 @@
+#' Generate all pages with facet_wrap_paginate
+#' 
+#' This is a wrapper for [facet_wrap_paginate()] to generate all of the pages,
+#' rather than just one at a time. 
+#' 
+#' @inheritParams facet_wrap_paginate
+#' @inheritDotParams facet_wrap_paginate
+#' @param plot A ggplot object.
+#' @return A list, where each element is one page of plots.
+#' @family ggforce facets
+#' @examples 
+#' g <- ggplot(diamonds, aes(x = cut, y = price)) + geom_boxplot()
+#' gl <- gen_all_pages_fwp(g, "color", nrow = 2, ncol = 3)
+#' gl[[1]]
+#' @export
+
+gen_all_pages_fwp <- function(plot, facets, ...){
+    dots <- list(...)
+    if (is.null(dots$nrow) || is.null(dots$ncol)){
+        msg <- paste("nrow and/or ncol is NULL. Please supply values for both",
+                     "arguments; otherwise, call facet_wrap directly.")
+        stop(msg)
+    }
+    n <- n_pages(plot + facet_wrap_paginate(facets, ..., page = 1))
+    plot_list <- lapply(1:n, function(i) {
+        plot + facet_wrap_paginate(facets, ..., page = i)
+    })
+    return(plot_list)
+}