Graphical Parameters The following is a list of arguments available to control the appearance of graphs. The following arguments can be specified within any graphical function to specify titles, where string is the title inserted in quotes, or a character vector containing the title: main="string" main title, above plot, in enlarged characters sub="string" sub-title for bottom of plot main="# of chin ups \n Females" for titles and sub-titles to run over more than one line, use \n in the character string to start a new line The following parameters may only be used in high-level graphical functions (those that set up coordinate systems, e.g., plot, qqplot). xlab="string", ylab="string" labels for the x an y axes axes= logical flag specifying axes=F forces Splus to omit drawing the axes xlim=, ylim= vectors giving the min and max values for the x and y axes Splus may extend the axes further to produce pretty tick labels log= specifies the axes to be logarithmic (ie.: log="xy") type= type of plot: "p" points "l" lines "b" both "o" both - overstruck "h" high density "n" null (sets up the axes to be filled in later) The function par() can be used to set graphical parameters which stay in effect throughout all plotting until they are reset in another call to par or by invoking a new graphic device. > par(mfrow=c(2,3)) * it is possible to specify the number and arrangement of graphs on a page using the mfrow= option * mfrow=c(2,3) allows 6 plots to appear on a page (2 rows of 6 plots each) * because the mfrow argument was used within the par function, the set up will stay in effect for all subsequent graphs > par(mfrow=c(1,1)) * restores the normal one-graph-per-page form * this could also be done by invoking a new graphic device > X11() > par(mfcol=c(3,2)) * the page is set up as above except that the graphs are printed columnwise, mfrow prints graphs row by row The following arguments can be specified either by the par() function or within a graphics function (for temporary parameter settings which stay in effect only for the call to the function and are then reset to their previous values). pch= plotting character, the default is pch="*" it is possible to specify either a character, using quotes, or a numeric value, causing Splus to use one of a set of predefined values: Basic symbols Superimposed symbols Filled in symbols 0 square 7 0 and 4 15 square 1 octagon 8 3 and 4 16 octagon 2 triangle 9 3 and 5 17 triangle 3 cross 10 1 and 3 18 diamond 4 X 11 2 and 6 5 diamond 12 0 and 3 6 inverted triangle 13 1 and 4 14 0 and 2 cex= character expansion, ie.: cex=0.5 gives half the standard character size lty= line type: a value of 1 gives solid lines, values of 2,3... will select a non-solid line type lwd= line width: the default value is 1. Increasing values produce thicker lines col= numeric color specification (default is 1) adj= string justification: 0 left justify 1 right justify 0.5 centre or any other fraction oma= a vector specifying the margins on each of the four sides of a multiple figure region: c(bottom, left, top, right) where the values specified are the number of lines of text ask= logical value ask=T means graphical device will prompt before going to the next page/screen of output (prevents plots from being erased before they are studied) lab= controls number of tick intervals and length of labels x= number of tick intervals on x axis (default = 5) y= number of tick intervals on y axis (default = 5) llen= length of labels on both axes (default = 7) eg.: lab=c(x=6, y=4, llen=9) las= type of axis labels: 0 parallel to axis 1 horizontal 2 perpendicular to axis For a list of all the available graphical parameters, type help(par) Other Useful FUnctions The arguments main= and sub= cannot be used from within these functions with the exception of title() points(x,y,pch= ) the function points() allows you to add variables to the current plot lines(x,y,lty= ) the function lines() allows you to add lines to the current plot abline adds a line to a plot arguments can be specified as: (a,b) where a = intercept and b = slope (coef) vector containing the intercept a and slope b (reg) a regression object (h= ) vector of y-coordinates for horizontal lines (v= ) vector of x-coordinates for vertical lines legend(x,y,legend= ) puts a box at the specified x,y coordinates with examples (if possible) of the lines/points/shading used in the graph identified by user-defined text identify(x,y,labels= ) similar to legend(), identify() prints text (labels) at the specified points locator(n= ,type= ) returns the coordinates specified interactively on a plot default is n=500, type="n" by changing type, points and/or lines may be added to the plot the locator() function can be used within the function legend() or identify() instead of specifying the x and y coordinates: legend(locator(1),legend) the point is identified by placing the cursor over the point and pressing the left mouse button to exit locator without identifying all "n" points, press the middle m ouse button title(main= , sub= , xlab= , ylab= ) adds titles and/or axis labels to the current plot will overwrite any existing titles and/or axis labels segments(x1,y1,x2,y2) adds a line segment with endpoints (x1,y1) and (x2,y2) to the current plot arrows(x1,y1,x2,y2) adds an arrow to the current plot for a description of optional arguments, type help(segments) text(x,y,labels) adds text to the current plot the coordinates can be given by two arguments (x and y) or by a single argument x which is a univariate time series, a complex vector, a matrix with 2 columns, or a list containing components named x and y mtext("string",side= ) adds text in the margins of the current plot side specifies the side on which the text is to be placed 1.bottom 2.left (default) 3.top 4.right other options are available for this function, use help(mtext) axis adds an axis to the current plot box surrounds the current plot with a box