r - Adding mean line and text label to lattice histogram -

aloha -

i creating series of histograms , add vertical line indicating mean value of distribution text label indicating sample size. code follows:

bin_width <- 1 #desired bin width print(histogram(~ length..cm. | method, #create , print histogram , save variable "graph" data = hist.data[hist.data$scientific_name == "pristipomoides filamentosus",],  nint = (max(hist.data$length..cm.) - min(hist.data$length..cm.)+1)/bin_width, layout = c(1,2), type = "density", main = "length-frequency of pristipomoides filamentosus gear", xlab = "length (cm)", panel = function(x, ...){     panel.histogram(x,...)     panel.mathdensity(dmath = dnorm, col = "red",                        args = list(mean = mean(x), sd= sd(x)), ...)     } )) 

i assumed done using panel.abline , panel.text functions inserted after panel.histogram, not seem working. doing wrong? if can give me code dummy vertical line (e.g. x=10) , dummy text, can insert equation mean , sample size.

you'll need panel.lines() , panel.text(). instance, following function puts horizontal line on barchart , annotates text, putting in customised legend:

function () {     trellis.device(width = 5, height = 5, new = f)     xx <- gerd95.06     xx$country <- c("usa", "singapore", "denmark", "australia",          "nz")     barchart(x1995 + x2006 ~ reorder(country, xx$x2006), data = xx,          ylab = "gerd per capita, nominal $us ppp", cex = 0.8,          panel = function(...) {             panel.lines(c(0.7, 5), c(720, 720), col = "gray",                  lwd = 4)             panel.text(lab = "oecd avg 2006", x = 1, y = 750,                  adj = c(0.4, 0), cex = 0.7)             panel.text(lab = "nz @ 2.5% of gdp", x = 1, y = 630,                  adj = c(0.4, 0), cex = 0.7)             panel.text(lab = "1995", x = 1.5, y = 900, adj = c(1,                  0.5))             panel.rect(xleft = 1.6, xright = 2, ybottom = 870,                  ytop = 930, col = 3)             panel.text(lab = "2006", x = 1.5, y = 1000, adj = c(1,                  0.5))             panel.rect(xleft = 1.6, xright = 2, ybottom = 970,                  ytop = 1030, col = 8)             panel.barchart(..., col = c(3, 8))             panel.rect(xleft = 1, xright = 1.3333, ybottom = xx$x2006[xx$country ==                  "nz"], ytop = 2.5/1.206 * xx$x2006[xx$country ==                  "nz"])         }, ylim = c(0, 1200)) } 

... produces graph: