HH (version 2.1-3)

intxplot: Interaction plot, with an option to print standard error bars.

Description

Interaction plot, with an option to print standard error bars. There is an option to offset group lines to prevent the bars from overprinting.

Usage

intxplot(x, data=sys.parent[1], groups.in,
          scales,
          key.length=1,
          key.lines,
          key=TRUE,
          trace.factor.name=deparse(substitute(groups.in)),
          x.factor.name=x.factor,
          xlab=x.factor.name,
          main=list(main.title, cex=main.cex),
          condition.name="condition",
          panel="panel.intxplot",
          summary.function="sufficient",
          se,
          ...,
          data.is.summary=FALSE,
          main.title=paste(
            "Interactions of", trace.factor.name, "and",
            x.factor.name,
            if (length(x[[3]]) > 1)
            paste("|", condition.name.to.use)),
          main.cex=1.5)

panel.intxplot(x, y, subscripts, groups, type = "l", ..., se, cv=1.96,
               offset.use=(!missing(groups) && !missing(se)),
               offset.scale=2*max(as.numeric(groups)),
               offset=
               as.numeric(groups[match(levels(groups), groups)]) / offset.scale,
               rug.use=offset.use)

Arguments

x
For intxplot, a formula with a factor as the predictor variable. For panel.intxplot, standard argument for panel functions.
data
data.frame, as used in xyplot.
groups.in
groups.in, as used in xyplot.
scales
Optional, additional arguments for the standard scales in xyplot.
key.length
Number of columns in the key.
key.lines
default value for the lines argument of key.
key
logical. If TRUE, draw the key.
trace.factor.name
Name of the grouping variable.
x.factor.name
name of the dependent variable.
xlab
as in xyplot, defaults to the name of the predictor variable from the formula.
main
as in xyplot. Defaults to the main.title argument.
panel
as in xyplot. Defaults to the "panel.intxplot".
condition.name
name of the conditioning variable.
summary.function
The default sufficient finds the mean, standard deviation, and sample size of the response variable for each level of the conditioning factor. See sufficient.
se
standard errors to be passed to panel.intxplot. se Missing, logical, or a numeric vector. If missing or FALSE, standard errors are not plotted. If se=TRUE in intxplot, th
...
In intxplot, arguments for panel.intxplot. In panel.intxplot, arguments for panel.superpose.
data.is.summary
logical, defaults to FALSE under the assumption that the input data.frame is the original data and the intxplot function will generate the summary information (primarily standard deviation sd and numbe
main.title
Default main title for plot.
main.cex
Default character expansion for main title.
y, subscripts, groups, type
Standard arguments for panel functions.
cv
critical value for confidence intervals. Defaults to 1.96.
offset.use
logical. If TRUE, offset the endpoints of each group.
offset.scale
Scale number indicating how far apart the ends of the groups will be placed. Larger numbers make them closer together.
offset
Actual numbers by which the end of the groups are offset from their nominal location which is the as.numeric of the group levels.
rug.use
logical. If TRUE, display a rug for the endpoints of each group.

Value

  • "trellis" object.

See Also

sufficient

Examples

Run this code
## This uses the same data as the HH Section 12.13 rhizobium example.

rhiz.clover <- read.table(hh("datasets/rhiz3-clover.dat"), header=TRUE)
rhiz.clover$comb <- factor(rhiz.clover$comb,
                         labels=c("clover","clover+alfalfa"))
position(rhiz.clover$comb) <- c(2,5)
rhiz.clover$strain <-
  factor(rhiz.clover$strain,
         labels=c('3DOk1','3DOk5','3DOk4','3DOk7','3DOk13','k.comp'))
rhiz.clover$Npg <- rhiz.clover$nitro / rhiz.clover$weight

## interaction plot, no se
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover)

## interaction plot, individual se for each treatment combination
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover, se=TRUE)

## Rescaled to allow the CI bars to stay within the plot region
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover, se=TRUE,
         ylim=range(rhiz.clover$Npg))

## interaction plot, common se based on ANOVA table
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover,
         se=sqrt(sum((nobs-1)*sd^2)/(sum(nobs-1)))/sqrt(5))

## Rescaled to allow the CI bars to stay within the plot region
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover,
         se=sqrt(sum((nobs-1)*sd^2)/(sum(nobs-1)))/sqrt(5),
         ylim=range(rhiz.clover$Npg))

## change distance between endpoints
intxplot(Npg ~ strain, groups=comb, data=rhiz.clover,
         se=TRUE, offset.scale=20)

## When data includes the nobs and sd variables, data.is.summary=TRUE is needed.
intxplot(Npg ~ strain, groups=comb,
         se=sqrt(sum((nobs-1)*sd^2)/(sum(nobs-1)))/sqrt(5),
         data=sufficient(rhiz.clover, y="Npg", c("strain","comb")),
         data.is.summary=TRUE,
         ylim=range(rhiz.clover$Npg))

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