Customizing Graphs Base graphics options. plot() The workhorse plotting function plot(x) plots...
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Transcript of Customizing Graphs Base graphics options. plot() The workhorse plotting function plot(x) plots...
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