| errbar {Hmisc} | R Documentation |
errbar adds vertical error bars to an existing plot or makes a new
plot with error bars. It can also make a horizontal error bar plot
that shows error bars for group differences as well as bars for
groups. For the latter type of plot, the lower x-axis scale
corresponds to group estimates and the upper scale corresponds to
differences. The spacings of the two scales are identical but the
scale for differences has its origin shifted so that zero may be
included. If at least one of the confidence intervals includes zero,
a vertical dotted reference line at zero is drawn.
errbar(x, y, yplus, yminus, cap, xlab, ylab, add=FALSE,
lty=1, ylim, lwd=1, Type=rep(1,length(y)), ... )
x |
vector of numeric x values (for vertical error bars) or a factor or
character variable (for horizontal error bars, x representing the
group labels)
|
y |
vector of y values. |
yplus |
vector of y values: the tops of the error bars. |
yminus |
vector of y values: the bottoms of the error bars. |
cap |
The width of the little lines at the tops and bottoms of the error bars in units of the width of the plot. Default is .015. |
xlab |
|
ylab |
optional axis labels if add=FALSE. Defaults to blank for horizontal charts.
|
add |
Set toTRUE to add bars to an existing plot (available only for vertical error bars) |
lty |
Line type for bars |
ylim |
Y-axis limits. Default is to use range of yminus and yplus. For
horizonal charts, ylim is really the x-axis range, excluding
differences.
|
lwd |
Line width for line segments (not main line) |
Type |
used for horizontal bars only. Is an integer vector with values 1
if corresponding values represent simple estimates, 2 if they
represent differences.
|
... |
other parameters passed to plot function. |
Charles Geyer, University of Chicago. Modified by Frank Harrell,
Vanderbilt University, to handle missing data, to add the parameters
add and lty, and to implement horizontal charts with differences.
set.seed(1)
x <- 1:10
y <- x + rnorm(10)
delta <- runif(10)
errbar( x, y, y + delta, y - delta )
# Show bootstrap nonparametric CLs for 3 group means and for
# pairwise differences on same graph
group <- sample(c('a','b','d'), 200, TRUE)
y <- runif(200) + .25*(group=='b') + .5*(group=='d')
cla <- smean.cl.boot(y[group=='a'],B=100,reps=TRUE) # usually B=1000
a <- attr(cla,'reps')
clb <- smean.cl.boot(y[group=='b'],B=100,reps=TRUE)
b <- attr(clb,'reps')
cld <- smean.cl.boot(y[group=='d'],B=100,reps=TRUE)
d <- attr(cld,'reps')
a.b <- quantile(a-b,c(.025,.975))
a.d <- quantile(a-d,c(.025,.975))
b.d <- quantile(b-d,c(.025,.975))
errbar(c('a','b','d','a - b','a - d','b - d'),
c(cla[1],clb[1],cld[1],cla[1]-clb[1],cla[1]-cld[1],clb[1]-cld[1]),
c(cla[3],clb[3],cld[3],a.b[2],a.d[2],b.d[2]),
c(cla[2],clb[2],cld[2],a.b[1],a.d[1],b.d[1]),
Type=c(1,1,1,2,2,2))
rm(x,y,delta,group,a,b,d,a.b,a.d,b.d,cla,clb,cld)