Enhanced Bar Plots

An enhancement of the standard barplot() function. Creates a bar plot with vertical or horizontal bars. Can plot confidence intervals for each bar, a lined grid behind the bars, change plot area color and logarithmic axes may be used.

# Default S3 method
barplot2(height, width = 1, space = NULL,
        names.arg = NULL, legend.text = NULL, beside = FALSE,
        horiz = FALSE, density = NULL, angle = 45,
        col = NULL, prcol = NULL, border = par("fg"),
        main = NULL, sub = NULL, xlab = NULL, ylab = NULL,
        xlim = NULL, ylim = NULL, xpd = TRUE, log = "",
        axes = TRUE, axisnames = TRUE,
        cex.axis = par("cex.axis"), cex.names = par("cex.axis"),
        inside = TRUE, plot = TRUE, axis.lty = 0, offset = 0,
        plot.ci = FALSE, ci.l = NULL, ci.u = NULL,
        ci.color = "black", ci.lty = "solid", ci.lwd = 1, ci.width = 0.5,
        plot.grid = FALSE, grid.inc = NULL,
        grid.lty = "dotted", grid.lwd = 1, grid.col = "black",
        add = FALSE, panel.first = NULL, panel.last = NULL, ...)

Arguments

height

either a vector or matrix of values describing the bars which make up the plot. If height is a vector, the plot consists of a sequence of rectangular bars with heights given by the values in the vector. If height is a matrix and beside is FALSE then each bar of the plot corresponds to a column of height, with the values in the column giving the heights of stacked “sub-bars” making up the bar. If height is a matrix and beside is TRUE, then the values in each column are juxtaposed rather than stacked.

width

optional vector of bar widths. Re-cycled to length the number of bars drawn. Specifying a single value will no visible effect unless xlim is specified.

space

the amount of space (as a fraction of the average bar width) left before each bar. May be given as a single number or one number per bar. If height is a matrix and beside is TRUE, space may be specified by two numbers, where the first is the space between bars in the same group, and the second the space between the groups. If not given explicitly, it defaults to c(0,1) if height is a matrix and beside is TRUE, and to 0.2 otherwise.

names.arg

a vector of names to be plotted below each bar or group of bars. If this argument is omitted, then the names are taken from the names attribute of height if this is a vector, or the column names if it is a matrix.

legend.text

a vector of text used to construct a legend for the plot, or a logical indicating whether a legend should be included. This is only useful when height is a matrix. In that case given legend labels should correspond to the rows of height; if legend.text is true, the row names of height will be used as labels if they are non-null.

beside

a logical value. If FALSE, the columns of height are portrayed as stacked bars, and if TRUE the columns are portrayed as juxtaposed bars.

horiz

a logical value. If FALSE, the bars are drawn vertically with the first bar to the left. If TRUE, the bars are drawn horizontally with the first at the bottom.

density

a vector giving the the density of shading lines, in lines per inch, for the bars or bar components. The default value of NULL means that no shading lines are drawn. Non-positive values of density also inhibit the drawing of shading lines.

angle

the slope of shading lines, given as an angle in degrees (counter-clockwise), for the bars or bar components.

col

a vector of colors for the bars or bar components. By default, grey is used if height is a vector, and heat.colors(nrow(height)) if height is a matrix.

prcol

the color to be used for the plot region.

border

the color to be used for the border of the bars.

main, sub

overall and sub titles for the plot.

xlab

a label for the x axis.

ylab

a label for the y axis.

xlim

limits for the x axis.

ylim

limits for the y axis.

xpd

logical. Should bars be allowed to go outside region?

log

a character string which contains `"x"' if the x axis is to be logarithmic, `"y"' if the y axis is to be logarithmic and `"xy"' or `"yx"' if both axes are to be logarithmic.

axes

logical. If TRUE, a vertical (or horizontal, if horiz is true) axis is drawn.

axisnames

logical. If TRUE, and if there are names.arg (see above), the other axis is drawn (with lty = 0) and labeled.

cex.axis

expansion factor for numeric axis labels.

cex.names

expansion factor for names.

inside

logical. If TRUE, the lines which divide adjacent (non-stacked!) bars will be drawn. Only applies when space = 0 (which it partly is when beside = TRUE).

plot

logical. If FALSE, nothing is plotted.

axis.lty

the graphics parameter lty applied to the axis and tick marks of the categorical (default horzontal) axis. Note that by default the axis is suppressed.

offset

a vector indicating how much the bars should be shifted relative to the x axis.

plot.ci

logical. If TRUE, confidence intervals are plotted over the bars. Note that if a stacked bar plot is generated, confidence intervals will not be plotted even if plot.ci = TRUE

ci.l,ci.u

The confidence intervals (ci.l = lower bound, ci.u = upper bound) to be plotted if plot.ci = TRUE. Values must have the same dim structure as height.

ci.color

the color for the confidence interval line segments

ci.lty

the line type for the confidence interval line segments

ci.lwd

the line width for the confidence interval line segments

ci.width

length of lines used for the "t" at the end of confidence interval line segments, as a multple of width. Defaults to 0.5.

plot.grid

if TRUE a lined grid will be plotted behind the bars

grid.inc

the number of grid increments to be plotted

grid.lty

the line type for the grid

grid.lwd

the line width for the grid

grid.col

the line color for the grid

add

logical, if TRUE add barplot to current plot.

panel.first

An expression to be evaluated after the plot region coordinates have been set up, but prior to the drawing of the bars and other plot region contents. This can be useful to add additional plot region content behind the bars. This will also work if add = TRUE

panel.last

An expression to be evaluated after the bars have been drawn, but prior to the addition of confidence intervals, a legend and the axis annotation

...

further graphical parameters (par) are passed to plot.window(), title() and axis.

Details

This is a generic function, it currently only has a default method. A formula interface may be added eventually.

Value

A numeric vector (or matrix, when beside = TRUE), say mp, giving the coordinates of all the bar midpoints drawn, useful for adding to the graph.

If beside is true, use colMeans(mp) for the midpoints of each group of bars, see example.

Author

Original barplot() by R-Core. Enhancements by Marc Schwartz.

Note

Prior to R 1.6.0, barplot behaved as if axis.lty = 1, unintentionally. 0 (zero) and NA values in height will not be plotted if using logarithmic scales. If there are NA values in height and beside = FALSE, values after the NA will not be plotted in stacked bars.

See also

plot(..., type = "h"), dotchart, hist.

Examples

tN <- table(Ni <- rpois(100, lambda = 5))
r <- barplot2(tN, col = 'gray')

#- type = "h" plotting *is* `bar'plot
lines(r, tN, type = 'h', col = 'red', lwd = 2)


barplot2(tN, space = 1.5, axisnames = FALSE,
        sub = "barplot2(..., space = 1.5, axisnames = FALSE)")


data(VADeaths, package = "datasets")
barplot2(VADeaths, plot = FALSE)
#> [1] 0.7 1.9 3.1 4.3
barplot2(VADeaths, plot = FALSE, beside = TRUE)
#>      [,1] [,2] [,3] [,4]
#> [1,]  1.5  7.5 13.5 19.5
#> [2,]  2.5  8.5 14.5 20.5
#> [3,]  3.5  9.5 15.5 21.5
#> [4,]  4.5 10.5 16.5 22.5
#> [5,]  5.5 11.5 17.5 23.5

mp <- barplot2(VADeaths) # default
tot <- colMeans(VADeaths)
text(mp, tot + 3, format(tot), xpd = TRUE, col = "blue")

barplot2(VADeaths, beside = TRUE,
        col = c("lightblue", "mistyrose", "lightcyan",
                "lavender", "cornsilk"),
        legend = rownames(VADeaths), ylim = c(0, 100))
title(main = "Death Rates in Virginia", font.main = 4)


# Example with confidence intervals and grid
hh <- t(VADeaths)[, 5:1]
mybarcol <- "gray20"
ci.l <- hh * 0.85
ci.u <- hh * 1.15
mp <- barplot2(hh, beside = TRUE,
        col = c("lightblue", "mistyrose",
                "lightcyan", "lavender"),
        legend = colnames(VADeaths), ylim = c(0, 100),
        main = "Death Rates in Virginia", font.main = 4,
        sub = "Faked 95 percent error bars", col.sub = mybarcol,
        cex.names = 1.5, plot.ci = TRUE, ci.l = ci.l, ci.u = ci.u,
        plot.grid = TRUE)
mtext(side = 1, at = colMeans(mp), line = -2,
      text = paste("Mean", formatC(colMeans(hh))), col = "red")
box()


# Example with horizontal bars, grid and logarithmic x axis
barplot2(1:10 , log = "x", plot.grid = TRUE, grid.inc = 10,
        xlim = c(0.5, 20), horiz = TRUE, cex.axis = 0.9,
        prcol = "gray95")
box()


# Bar shading example
barplot2(VADeaths, angle = 15 + 10 * 1:5, density = 20, col = "black",
        legend = rownames(VADeaths))
title(main = list("Death Rates in Virginia", font = 4))


# border :
barplot2(VADeaths, border = "dark blue")