barplot               package:graphics               R Documentation

Bar Plots

Description:

     Creates a bar plot with vertical or horizontal bars.

Usage:

     barplot(height, ...)

     ## Default S3 method:
     barplot(height, width = 1, space = NULL,
             names.arg = NULL, legend.text = NULL, beside = FALSE,
             horiz = FALSE, density = NULL, angle = 45,
             col = 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,
             add = FALSE, ...)

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 have 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 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 a
          gamma-corrected grey palette if 'height' is a matrix.

  border: the color to be used for the border of the bars. Use 'border
          = NA' to omit borders.  If there are shading lines, 'border =
          TRUE' means use the same colour for the border as for the
          shading lines.

main,sub: overall and sub title 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: string specifying if axis scales should be logarithmic; see
          'plot.default'.

    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 axis names (bar labels).

  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 horizontal) 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.

     add: logical specifying if bars should be added to an already
          existing plot; defaults to 'FALSE'.

     ...: arguments to be passed to/from other methods.  For the
          default method these can include further arguments (such as
          'axes', 'asp' and 'main') and graphical parameters (see
          'par') which 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.

References:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

     Murrell, P. (2005) _R Graphics_. Chapman & Hall/CRC Press.

See Also:

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

Examples:

     require(grDevices) # for colours
     tN <- table(Ni <- stats::rpois(100, lambda=5))
     r <- barplot(tN, col=rainbow(20))
     #- type = "h" plotting *is* 'bar'plot
     lines(r, tN, type='h', col='red', lwd=2)

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

     barplot(VADeaths, plot = FALSE)
     barplot(VADeaths, plot = FALSE, beside = TRUE)

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

     hh <- t(VADeaths)[, 5:1]
     mybarcol <- "gray20"
     mp <- barplot(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 upper 2*sigma error bars", col.sub = mybarcol,
             cex.names = 1.5)
     segments(mp, hh, mp, hh + 2*sqrt(1000*hh/100), col = mybarcol, lwd = 1.5)
     stopifnot(dim(mp) == dim(hh))# corresponding matrices
     mtext(side = 1, at = colMeans(mp), line = -2,
           text = paste("Mean", formatC(colMeans(hh))), col = "red")

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

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

     # log scales (not much sense here):
     barplot(tN, col=heat.colors(12), log = "y")
     barplot(tN, col=gray.colors(20), log = "xy")

