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lessR (version 2.4.2)

LineChart: Run Chart or Time-Series Chart

Description

Abbreviation: rc

Plots a line chart, the values of the variable ordered according to their order in the data frame. Usually this ordering would be an ordering according to time, which yields a run chart. The default run chart provides the index, that is, sequential position, of each value of the variable from 1 to the last value. Optionally dates can be provided so that a time-series plot is produced.

For data of one variable exhibiting little trend, the center line is provided for the generation of a run chart, plotting the values of a variable in order of occurrence over time. When the center line, the median by default, is plotted, the analyses of the number and composition of the individual runs, number of consecutive values above or below the center line, is also displayed. Also, the defaults change for each of the types of plots. The intent is to rely on the default values for a relatively sophisticated plot, particularly when compared to the default values of the standard R plot function called with a single variable.

Usage

LineChart(y, dframe=mydata, type=NULL, 

col.line=NULL, col.area=NULL, col.box="black", col.pts=NULL, col.fill=NULL, trans.pts=getOption("trans.pts"), shape.pts=21, col.grid=NULL, col.bg=NULL, colors=c("blue", "gray", "rose", "green", "gold", "red"),

cex.axis=.85, col.axis="gray30", col.ticks="gray30", xy.ticks=TRUE, xlab=NULL, ylab=NULL, main=NULL, cex=NULL, x.start=NULL, x.end=NULL, y.start=NULL, y.end=NULL, time.start=NULL, time.by=NULL, time.reverse=FALSE,

center.line=c("default", "mean", "median", "off"), text.out=TRUE,

pdf.file=NULL, pdf.width=5, pdf.height=5, ...)

lc(...)

Arguments

y
Variable for which to construct the line chart, values on the vertical axis.
dframe
Data frame that contains the variable of interest, default is mydata.
type
Character string that indicates the type of plot, either "p" for points, "l" for line, or "b" for both. If x and y are provided and x is sorted so that a function is plotted, the default is "
col.line
Color of any plotted line segments, with a default of "darkblue".
col.area
Color of area under the plotted line segments. To have a border at the bottom and right of a run chart but retain the property of no area color, specify a color of "transparent". If the values exhibit a trend and dates
col.box
Color of border around the plot background, the box, that encloses the plot, with a default of "black".
col.pts
Color of the border of the plotted points.
col.fill
For plotted points, the interior color of the point. For a scatterplot the default value is transparent. For a run chart the default value is the color of the point's border, col.pts.
trans.pts
Transparency of the plotted points, from opaque at 0 to perfectly transparent at 1. Default is 0.6
shape.pts
The standard plot character, with values defined in help(points). The default value is 21, a circle with both a border and filled area, specified here as col.pts and col.fill. For a scatterplot, col.fill
col.grid
Color of the grid lines, with a default of "grey90".
col.bg
Color of the plot background.
colors
Sets the color palette.
cex.axis
Scale magnification factor, which by defaults displays the axis values to be smaller than the axis labels.
col.axis
Color of the font used to label the axis values.
col.ticks
Color of the ticks used to label the axis values.
xy.ticks
Flag that indicates if tick marks and associated values on the axes are to be displayed.
xlab
Label for x-axis. For two variables specified, x and y, if xlab not specified, then the label becomes the name of the corresponding variable. If xy.ticks is FALSE, then no label is displayed. If no y v
ylab
Label for y-axis. If not specified, then the label becomes the name of the corresponding variable. If xy.ticks is FALSE, then no label displayed.
main
Label for the title of the graph. If the corresponding variable labels exist in the data frame mylabels, then the title is set by default from the corresponding variable labels.
cex
Magnification factor for any displayed points, with default of cex=1.0.
x.start
For Likert style response data, the starting integer value of the x-axis. Useful if the actual data do not include all possible values.
x.end
For Likert style response data, the ending integer value of the x-axis. Useful if the actual data do not include all possible values.
y.start
For Likert style response data, the starting integer value of the y-axis. Useful if the actual data do not include all possible values.
y.end
For Likert style response data, the ending integer value of the y-axis. Useful if the actual data do not include all possible values.
time.start
Optional starting date for first data value. Format must be "%Y-%m-%d" or "%Y/%m/%d". If using with x.reverse, the first date is after the data are reverse sorted. Not needed if data are a time series with
time.by
Accompanies the time.start specification, the interval to increment the date for each sequential data value. A character string, containing one of "day", "week", "month" or "year"
time.reverse
When TRUE, reverse the ordering of the dates, particularly when the data are listed such that first row of data is the newest. Accompanies the time.start specification.
center.line
Plots a dashed line through the middle of a run chart. The two possible values for the line are "mean" and "median". Provides a centerline for the "median" by default when the values randomly vary about
text.out
If TRUE, then display text output in console.
pdf.file
Name of the pdf file to which graphics are redirected.
pdf.width
Width of the pdf file in inches.
pdf.height
Height of the pdf file in inches.
...
Other parameters such as from par.

Details

OVERVIEW The line chart is based on the standard R function plot when called with only a single variable.

The values on the horizontal axis of the line chart are automatically generated. The default is the index variable, the ordinal position of each data value, in which case this version of the line chart is a run chart. Or, dates on the horizontal axis can be specified from the specified starting date given by x.start and the accompanying increment as given by x.by, in which case the line chart is typically referred to as a time series chart.

If the data values randomly vary about the mean, the default is to plot the mean as the center line of the graph, otherwise the default is to ignore the center line. The default plot type for the line chart is type="b", for both points and the corresponding connected line segments. The size of the points is automatically reduced according to the number of points of points plotted, and the cex option can override the computed default. If the area below the plotted values is specified to be filled in with color, then the default line type changes to type="l".

DATA If the variable is in a data frame, the input data frame has the assumed name of mydata. If this data frame is named something different, then specify the name with the dframe option. Regardless of its name, the data frame need not be attached to reference the variable directly by its name, that is, no need to invoke the mydata$name notation.

COLOR THEME Individual colors in the plot can be manipulated with options such as col.pts for the color of the plotted points. A color theme for all the colors can be chosen for a specific plot with the colors option. Or, the color theme can be changed for all subsequent graphical analysis 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.

VARIABLE LABELS Although standard R does not provide for variable labels, lessR can store the labels in a data frame called mylabels, obtained from the Read function. If this labels data frame exists, 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:

> LineChart(rnorm(50)) # does NOT work}

Instead, do the following: > Y <- rnorm(50) # create vector Y in user workspace > LineChart(Y) # directly reference Y

[object Object],[object Object]

plot, set.

# generate 25 random normal data values y <- rnorm(25)

# default run chart LineChart(y) # short name lc(y) # compare to standard R plot plot(y, type="l")

# save run chart to a pdf file LineChart(y, pdf.file="MyLineChart.pdf")

# LineChart in gray scale LineChart(y, colors="gray") # customize run chart, pch=24: filled triangle point-up, LineChart(y, lwd=2, col.pts="sienna3", shape.pts=24, col.bg="mintcream", ylim=c(-3.5,3.5), center.line="median") # generate steadily increasing values y <- sort(rexp(50)) # default line chart LineChart(y) # line chart with border around plotted values LineChart(y, col.area="transparent") # time series chart, i.e., with dates, and filled area # with option label for the x-axis LineChart(y, time.start="2005/09/01", time.by="month") # time series chart from a time series object y.ts <- ts(y, start=c(2005, 9), frequency=12) LineChart(y.ts)

# LineChart with built-in data set LineChart(breaks, dframe=warpbreaks)plot line chart run chart time series chart