customizing graphs
DESCRIPTION
Customizing Graphs. Base graphics options. plot(). The workhorse plotting function plot(x) plots values of x in sequence or a barplot plot(x, y) produces a scatterplot plot( y~x , data= data.frame ) produces a scatterplot - PowerPoint PPT PresentationTRANSCRIPT
Customizing Graphs
Base graphics options
plot()• The workhorse plotting function• plot(x) plots values of x in
sequence or a barplot• plot(x, y) produces a scatterplot• plot(y~x, data=data.frame)
produces a scatterplot• Many statistical functions produce
results that can be plotted using plot
Variations on plot()• type = “p”, “l”, “b”, or “n” for
points, lines, both, or no plot (also “c”, “o”, “h”, “s”, “S”)
• asp = sets the y/x aspect ratio (asp=1 for mapping)
• Full control over labels, axes, symbols, lines, etc
Parameter cex=• cex controls the size of text and
symbols in a graph• cex = 1 is the default size (except
for main= where it is 2)• cex.main, cex.sub, cex.lab,
cex.axis control specific parts of the plot
• cex = alone usually controls the size of pch, the plot character
Symbol/Line Styles• pch = (plot character) specifies the
symbol set• cex = symbol size• lty = specifies the line type• lwd = specifies the line thickness
Parameter col=• col = controls the color of a symbol
or line• col.axis, col.lab, col.main, col.sub
control colors of other parts of the graph
• bg = background color• col takes a name or hexadecimal
color value
Color• colors() for list of 657 named
colors• palette() gives the default list of
eight colors• gray() gives grayscale from black -
gray(0) to white – gray(1)
Color Palettes• rainbow(number) generates a
spectrum from red to violet based on hue, saturation, and value (hsv)
• rainbow_hcl(number) similar, but using hue, chroma, and luminance color space (hcl)
• Help pages for these give several other palettes
Fonts• family = sets the font family –
“serif”, “sans”, and “mono” – others may be defined by specific graphic devices
• font = sets the font, 1 plain, 2 bold, 3 italic, 4 bold italic, 5 symbol
• Fonts may be device dependent
Labels• main = “This is the title”,
cex.main, col.main, font.main• sub = “This is the subtitle”,
cex.sub, col.sub, font.sub• Axis labels
– lab = “This is the x-axis label”– ylab = “This is the y-axis label”– cex.lab, col.lab, font.lab, las (0, 1, 2,
3)
Axes• Default usually selects reasonable
axes• xlim, ylim set limits for axes• xaxp, yaxp set tick marks• xlog, ylog to use log scale• xaxt , yaxt “n” suppresses plotting
axis()• Use to add a customized axis or
position an axis on the top or right of the plot or in the margin of the plot
• at = specifies location of tickmarks• labels = specifies labels
Adding to a Graph 1• Plot sets up coordinates• grid – add gridlines• abline – add regression, vertical, or
horizontal lines (full plot window)• points – add points• lines – add lines• segment – add line segments
Adding to a Graph 2• text – add text to plot• legend (locator, position, coords)• arrows – draw arrows• rect – draw rectangles• polygon – draw polygons• ellipse – draw probability ellipse• matlines – draw multiple lines
Margins• Must be set before calling plot• oldpar <- par() # to save current• par(mar= c(bottom, left, top,
right)) if you need more space for labels, titles, etc
Multiple Graphs• par(mfrow=c(rows, cols)) plots in
rows• Par(mfcol=c(rows, cols)) plots in
columns