6601 Project---Graphics

1. 6601 Project---Graphics --Enhancing Plots --Fine Control of Graphics Xingyan Bai, Qian Zhang, Ying Li

2. Enhancing Plots • Multiple figures on one plot • Adding information • Using Color • Identifying points interactively • Adding further axes and grids • Adding legends • Mathematics in labels

3. Multiple figures on one plot • par(mfrow = c(…)) par(mfcol = c(…)) • split.screen(figs, screen, …) screen(n = , …) erase.screen(n = ) close.screen(n, …) • subplot(fun, …) in S-plus

4. Multiple figures on one plot Example Code: split.screen(figs=c(3,2)) [1] 1 2 3 4 5 6 hist(t.stars, nclass=20, prob=TRUE) screen(3) hist(t.stars, nclass=10, prob=TRUE) screen(6) hist(t.stars, nclass=30, prob=TRUE)

6. Multiple figures on one plot Example Code: par(mfrow=c(2,3)) hist(t.stars, nclass=20, prob=TRUE) hist(t.stars, nclass=10, prob=TRUE) hist(t.stars, nclass=30, prob=TRUE) hist(t.stars, nclass=5, prob=TRUE) hist(t.stars, nclass=15, prob=TRUE) hist(t.stars, nclass=50, prob=TRUE)

8. Using Color Code par(mfrow=c(2,1)) hist(t.stars, nclass=20, prob=TRUE, col='gray', border='white') hist(t.stars, nclass=10, prob=TRUE, col='green', border='red')

9. Identifying points interactively Code par(mfrow=c(1,1)) plot(data$x, data$y) identify(data$x,data$y) [1] 3 26 38 56 83 87 90

10. Identifying points using locator() Code locator(5,type='l') $x [1] -99.78800 -25.17453 51.60166 124.05243 182.44558 $y [1] -49.04550 40.17314 111.34755 138.41388 164.47775

11. Adding further axes and grids Code > library(MASS) > attach(wtloss) > oldpar <- par() > par(mar = c(5.1, 4.1, 4.1, 4.1)) > plot(Days, Weight, type = "p", ylab = "Weight (kg)") > Wt.lbs <- pretty(range(Weight*2.205)) > axis(side = 4, at = Wt.lbs/2.205, lab = Wt.lbs, srt = 90) > mtext("Weight (lb)", side = 4, line = 3) > detach() > par(oldpar)

12. Adding further axes and grids

13. Adding legends Code plot(ecdf(y), main='Empirical Distribution of Y') curve(pexp(x, 1/mean(y)), add=TRUE, col='red') legend(200, 0.6, c('EDF','Fitted model (Exponential)'), + lty=c(1,1), col=c('black','red'))

14. Fine Control of Graphics • Par Command • Figure region and layout parameters • Common axes for figures

15. Par Command • Par ( name = value) set value to name • Par (name) return the value of name • Par () return a list of all the graphics parameters

16. Figure region and layout parameters • Regions: plot region, margins, figure region, device region • Layout parameters: control size and position of figure and plot regions mar()/mai(): for margin region, fig(): for figure as a fraction of device region, plt(): for plot as a fraction of figure region. • User coordinates: for positions in the plot region

17. Example for layout parameters Code x <- rnorm(50) y <- rnorm(x) z <- rexp(x) par(fig = c(0, 2/3, 0, 1)) plot(x, y) par(fig = c(2/3, 1, 0, 1)) plot(x, z) par("usr") [1] -2.1027427 2.1591728 -0.1081944 3.7349138

18. Example for layout parameters

19. Common axes for figures • Use the same xlim or ylim • Set up the desired axis system with the first plot and then use Par to set the low-level parameter xaxs = “d” & yaxs = “d”, which (direct) specifies that the current axis should be used on subsequent plots. • Some of the more commonly used general and high-level graphics parameters see Table4.4(page 87)

20. Thank You!