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--- documents:111012rtricks [2012/02/14 21:37] – kota
+++ documents:111012rtricks [2012/06/13 12:38] – kota
@@ Line 52: / Line 52: @@
 [{{:documents:rtips:imageplot.png| Example plotting of a matrix using base graphics function image()}}]
+... a bit faster way calculation wise uses indexing.
+<sxh>
+width <- 10
+height <- 20
+x <- c(1:width)
+y <- c(1:height)
+xindex <-rep(x, length = width*height)
+yindex <- yindexing(x, y)
+z <- xindex + yindex
+z <- matrix(z, nrow=width, ncol=height)
+mat <- list(x, y, z)
+image(x, y, z)
+yindexing <- function (x, y) {
+  for(i in y){
+    cr <- rep(i, length=length(x))
+    if (i==1) all <- cr
+    else all <- append(all, cr)
+  }
+  return (all)
+}
+</sxh>
+===== Inserting math formula & symbols in label or title =====
+The easiest way is to use function //expression()//. For example,
+<code>
+plot(back$V2, type='l', xlab=expression(slice %.% time), ylab='intensity', xaxt="n", yaxt="n")
+</code>
+Inserts vertically centered dot in the x label between "slice" and "time". You could check other available expressions by
+<code>
+?plotmath
+</code>
+More recent, but under development is using [[http://cran.r-project.org/web/packages/tikzDevice/|tikzDevice]].