Merge pull request #908 from jimhester/one_limit

Allow NA in limits

Author: hadley

NEWS

@@ -1,6 +1,10 @@
 ggplot2 0.9.3.1.99
 ----------------------------------------------------------------
 
+* Allow specifying only one of the limits in a scale and use the automatic
+  calculation of the other limit by passing NA to to the limit function (xlim
+  or ylim). (Fixes #557)  Thanks Jim Hester.
+
 * `stat_smooth()` checks for `method = "auto"` and `method = "glm"` in
   a safer way.
 
@@ -13,6 +17,11 @@ ggplot2 0.9.3.1.99
 * Add `"none"` to documentation of `theme()` for parameter `legend.position`.
   (@krlmlr, #829)
 
+MINOR FEATURES
+
+* Allow specifying only one of the limits in a scale and use the automatic
+  calculation of the other limit by passing NA to to the limit function (xlim
+  or ylim). (Fixes #557)  Thanks Jim Hester.
 
 ggplot2 0.9.3.1
 ----------------------------------------------------------------

R/limits.r

@@ -1,7 +1,8 @@
 #' Convenience functions to set the limits of the x and y axis.
 #'
 #' Observations not in this range will be dropped completely and
-#' not passed to any other layers.
+#' not passed to any other layers.  If a NA value is substituted for one of the
+#' limits that limit is automatically calculated.
 #'
 #' @param ... if numeric, will create a continuous scale, if factor or
 #'   character, will create a discrete scale.
@@ -16,12 +17,16 @@
 #' xlim(c(10, 20))
 #' xlim("a", "b", "c")
 #' qplot(mpg, wt, data=mtcars) + xlim(15, 20)
+#' # with automatic lower limit
+#' qplot(mpg, wt, data=mtcars) + xlim(NA, 20)
 #'
 #' # ylim
 #' ylim(15, 20)
 #' ylim(c(10, 20))
 #' ylim("a", "b", "c")
-#' qplot(mpg, wt, data=mtcars) + ylim(15, 20)
+#' qplot(mpg, wt, data=mtcars) + ylim(0, 4)
+#' # with automatic upper limit
+#' qplot(mpg, wt, data=mtcars) + ylim(0, NA)
 xlim <- function(...) {
   limits(c(...), "x")
 }
@@ -47,7 +52,7 @@ limits <- function(lims, var) UseMethod("limits")
 #' @export
 limits.numeric <- function(lims, var) {
   stopifnot(length(lims) == 2)
-  if (lims[1] > lims[2]) {
+  if (!any(is.na(lims)) && lims[1] > lims[2]) {
     trans <- "reverse"
   } else {
     trans <- "identity"

R/scale-.r

@@ -296,9 +296,16 @@ scale_limits <- function(scale) {
 }
 
 
+#  if scale contains a NULL, use the default scale range
+#  if scale contains a NA, use the default range for that axis, otherwise
+#  use the user defined limit for that axis
 #' @export
 scale_limits.default <- function(scale) {
-  scale$limits %||% scale$range$range
+  if(!is.null(scale$limits)) {
+    ifelse(!is.na(scale$limits), scale$limits, scale$range$range)
+  } else {
+    scale$range$range
+  }
 }
 
 # @kohske

man/xylim.Rd

@@ -14,7 +14,8 @@ ylim(...)
 }
 \description{
 Observations not in this range will be dropped completely and
-not passed to any other layers.
+not passed to any other layers.  If a NA value is substituted for one of the
+limits that limit is automatically calculated.
 }
 \examples{
 # xlim
@@ -23,12 +24,16 @@ xlim(20, 15)
 xlim(c(10, 20))
 xlim("a", "b", "c")
 qplot(mpg, wt, data=mtcars) + xlim(15, 20)
+# with automatic lower limit
+qplot(mpg, wt, data=mtcars) + xlim(NA, 20)
 
 # ylim
 ylim(15, 20)
 ylim(c(10, 20))
 ylim("a", "b", "c")
-qplot(mpg, wt, data=mtcars) + ylim(15, 20)
+qplot(mpg, wt, data=mtcars) + ylim(0, 4)
+# with automatic upper limit
+qplot(mpg, wt, data=mtcars) + ylim(0, NA)
 }
 \seealso{
 For changing x or y axis limits \strong{without} dropping data