qbar: Draw a bar plot
In ggobi/cranvas: Interactive statistical graphics based on Qt

Description Usage Arguments Details Value Author(s) See Also Examples

This function creates a bar plot based on a categorical variable to show the counts of all categories. Another categorical variable can be used to further split each bar into sub-categories, which will make the bar plot a representation of a contingency table. The splitting variable can be specified in qdata using either the color argument or the border argument.

1 2	qbar(x, data, weight = NULL, space = 0.1, main = "", horizontal = FALSE, standardize = FALSE, xlim = NULL, ylim = NULL, xlab = NULL, ylab = NULL)

`x`	a variable name (will be coerced to a factor if it is not; `NA` will also be a level of the factor if the variable has any `NA`'s)
`data`	a mutaframe created by `qdata`
`weight`	weight the bars by the sums of another variable instead of the counts of `x`
`space`	the space between bars proportional to the width of bars
`main`	the main title
`horizontal`	`TRUE` to draw a horizontal plot or `FALSE` (vertical)
`standardize`	logical: whether to standardize the height of each bar to 1
`xlim`	a numeric vector of length 2 (like `c(x0, x1)`) for x-axis limits; it will be calculated from the data limits if not specified (`NULL`). Note when `x0 > x1`, the axis direction will be reversed (i.e. from larger values to small values)
`ylim`	y-axis limits; similar to `xlim`
`xlab`	x-axis title
`ylab`	y-axis title

All the common interactions like brushing and deleting are documented in common_key_press.

In the identify mode (press the key ? to toggle between brush and identify mode), the variable and its identified values are shown as a text label in the plot, along with the counts and proportion of the identified categories. If the bar plot is split by an additional categorical variable, it will also be shown in the label.

A zero-count category is represented by a one-pixel rectangle, which is a useful visual hint to indicate the presence of this category.

The x-axis (or y-axis when horizontal = TRUE) tickmark locations are from 1 to n shifted to the right by 0.5 (i.e. 1.5, 2.5, ...), where n is the number of levels of the factor variable to be plotted.

A bar plot

Yihui Xie <http://yihui.name>

Other plots: qboxplot; qdensity; qhist, qspine; qmval; qparallel; qtime

library(cranvas)
## tennis data

qtennis <- qdata(tennis)
qbar(matches, data = qtennis)
qbar(matches, data = qtennis, weight = serve.speed)

## NRC rankings

qnrc <- qdata(nrcstat, color = Control)  # Control: public or private univ
qbar(RegCode, data = qnrc, main = "Number of public and private colleges in each region")

qparallel(vars = 13:10, data = qnrc, main = "Overview of Rankings", glyph = "tick", 
    horizontal = TRUE, boxplot = TRUE)

qbar(RegCode, data = qnrc, horizontal = TRUE)  # horizontal plot
qbar(RegCode, data = qnrc, standardize = TRUE)  # standardize to 1

## use border color to split the bars
qnrc2 <- qdata(nrcstat, color = "white", border = Control)
qbar(RegCode, data = qnrc2)

## happy data
library(productplots)
qhappy <- qdata(happy, color = happy)
qbar(happy, data = qhappy)

cranvas_off()