Add function timeplot(), like grayplot() but with x-axis as date/time

NAMESPACE

@@ -67,6 +67,7 @@ export(strwidth2xlim)
 export(switchv)
 export(theme_karl)
 export(time_axis)
+export(timeplot)
 export(trap)
 export(triarrow)
 export(trigrid)

R/timeplot.R

@@ -0,0 +1,49 @@
+#' Scatterplot with date/times on the x-axis
+#'
+#' Like the [grayplot()] function, but with the x-axis having date/times
+#'
+#' @param x X-axis coordinates of points for the plot (must be date/time values)
+#'
+#' @param y Y-axis coordinates of points for the plot
+#'
+#' @param ... Optional graphics arguments passed to [grayplot()]
+#'
+#' @param n Approximate number of x-axis labels (passed to [base::pretty()]).
+#'
+#' @param scale Passed to [time_axis()] for defining the x-axis labels
+#'
+#' @param format Passed to [time_axis()] for defining the x-axis labels
+#'
+#' @return None.
+#'
+#' @export
+#'
+#' @importFrom graphics axis
+#'
+#' @examples
+#' n <- 100
+#' y <- rnorm(n)
+#' x <- seq(as.POSIXct("2024-05-01 11:23"), as.POSIXct("2024-05-01 14:50"), length.out=n)
+#' timeplot(x, y)
+
+timeplot <-
+    function(x, y, ..., n=5, scale=NULL, format=NULL)
+{
+    xax <- time_axis(x, n, scale, format)
+
+    timeplot_internal <-
+        function(x, y, vlines=NULL, mgp=c(2, 0.5, 0), mgp.x=NULL, mgp.y=NULL, ...)
+    {
+        if(is.null(vlines)) vlines <- xax$x
+
+        if(is.null(mgp.x)) mgp.x <- mgp
+        if(is.null(mgp.y)) mgp.y <- mgp
+
+        grayplot(x, y, xat=NA, vlines=vlines, mgp=mgp, mgp.x=mgp.x, mgp.y=mgp.y, ...)
+
+        axis(side=1, at=xax$x, labels=xax$labels, tick=FALSE, mgp=mgp.x)
+    }
+
+    timeplot_internal(x, y, ...)
+    invisible()
+}