bxUses the standard R boxplot function, boxplot to display a boxplot in color. Also display the relevant statistics such as the hinges, median and IQR.
If the provided object for which to calculate the box plot is a data frame, then a box plot is calculated for each numeric variable in the data frame and the results written to a pdf file in the current working directory. The name of this file and its path are specified in the output.
BoxPlot(x=NULL, data=mydata, n.cat=getOption("n.cat"), col.fill=getOption("col.fill.bar"),
col.stroke=getOption("col.stroke.bar"),
col.bg=getOption("col.bg"),
col.grid=getOption("col.grid"),
cex.axis=.85, col.axis="gray30", col.ticks="gray30",
xlab=NULL, main=NULL, digits.d=NULL,
horiz=TRUE, add.points=FALSE,
quiet=getOption("quiet"),
pdf.file=NULL, pdf.width=5, pdf.height=5, ...)
bx(...)
data, that is, no variable specified, then the
data frame mydata is assumed.mydata.cex.axis.FALSE for vertical.TRUE, then place a dot plot (i.e., stripchart) over the
box plot.TRUE, no text output. Can change system default with
set function.boxplot, the default here is for a horizontal boxplot. Also, BoxPlot does not currently process in formula mode, so use the standard R boxplot function to process a formula in which a boxplot is displayed for a variable at each level of a second, usually categorical, variable.Other graphic parameters are available to format the display, such as main for the title, and other parameters found in boxplot and par. To minimize white space around the boxplot, re-size the graphics window before or after creating the boxplot.
DATA
The data may either be a vector from the global enviornment, the user's workspace, as illustrated in the examples below, or a variable in a data frame. The default input data frame is mydata. Specify a different data frame name with the data option. Regardless of its name, the variables in the data frame are referenced directly by their names, that is, no need to invoke the standard R mechanisms of the mydata$name notation, the with function or the attach function. If the name of vector in the global environment and of a variable in the input data frame are the same, the vector is analyzed.
To obtain a box plot of each numerical variable in the mydata data frame, use BoxPlot(). Or, for a data frame with a different name, insert the name between the parentheses.
COLORS
Individual colors in the plot can be manipulated with options such as col.bars for the color of the histogram bars. A color theme for all the colors can be chosen for a specific plot with the colors option with the lessR function set. The default color theme is blue, but a gray scale is available with "gray", and other themes are available as explained in set, such as "red" and "green". Use the option ghost=TRUE for a black background, no grid lines and partial transparency of plotted colors.
VARIABLE LABELS
If variable labels , then the corresponding variable label is by default listed as the label for the horizontal axis and on the text output. For more information, see Read.
PDF OUTPUT
Because of the customized graphic windowing system that maintains a unique graphic window for the Help function, the standard graphic output functions such as pdf do not work with the lessR graphics functions. Instead, to obtain pdf output, use the pdf.file option, perhaps with the optional pdf.width and pdf.height options. These files are written to the default working directory, which can be explicitly specified with the R setwd function.
ONLY VARIABLES ARE REFERENCED
The referenced variable in a lessR function can only be a variable name. This referenced variable must exist in either the referenced data frame, mydata by default, or in the user's workspace, more formally called the global environment. That is, expressions cannot be directly evaluated. For example:
> BoxPlot(rnorm(50)) # does NOT work}
Instead, do the following: > Y <- rnorm(50) # create vector Y in user workspace > BoxPlot(Y) # directly reference Y
R function boxplot, invisibly returns a list with components described in boxplot.
[object Object],[object Object]
# ------------------------------ # box plot for a single variable # ------------------------------
# standard horizontal boxplot with all defaults BoxPlot(y)
# short name bx(y)
# save the box plot to a pdf file BoxPlot(y, pdf.file="MyBoxPlot.pdf")
# vertical boxplot with plum color BoxPlot(y, horiz=FALSE, col.fill="plum")
# box plot with outliers more strongly highlighted BoxPlot(y, col.stroke="red", xlab="My Variable")
# ------------------------------------------------ # box plots for data frames and multiple variables # ------------------------------------------------
# create data frame, mydata, to mimic reading data with rad function # mydata contains both numeric and non-numeric data mydata <- data.frame(rnorm(100), rnorm(100), rnorm(100), rep(c("A","B"),50)) names(mydata) <- c("X","Y","Z","C")
# box plot for variable X from data frame, referred to directly BoxPlot(X)
# box plot with superimposed dot plot (stripchart) BoxPlot(X, dotplot=TRUE)
# box plots for all numeric variables in data frame called mydata BoxPlot()
# box plots for all numeric variables in data frame called mydata # with specified options BoxPlot(col.fill="palegreen1", col.stroke="plum")
# Use the subset function to specify a variable list
mysub <- subset(mydata, select=c(X,Y))
BoxPlot(data=mysub)