# [R] How to add legend of plot.Design function ( method=image)?

From: Jan Verbesselt <Jan.Verbesselt_at_biw.kuleuven.be>
Date: Tue 23 Aug 2005 - 00:58:48 EST

Dear Rlist,

How can the Legend of the plot.Design() function can be visualized?

Following the documentation in R, I did the following (see below), only the 'Legend' function doesn't visualize the legend of the

plot (method='image') of the lrmfit. I tried to change par( margin setting) but this didn’t solve it.

How can this be solved?

Thanks a lot,

Jan

library(Design)

n <- 1000 # define sample size

set.seed(17) # so can reproduce the results

age <- rnorm(n, 50, 10)

blood.pressure <- rnorm(n, 120, 15)

cholesterol <- rnorm(n, 200, 25)

sex <- factor(sample(c('female','male'), n,TRUE))

label(age) <- 'Age' # label is in Hmisc

label(cholesterol) <- 'Total Cholesterol'

label(blood.pressure) <- 'Systolic Blood Pressure'

label(sex) <- 'Sex'

units(cholesterol) <- 'mg/dl' # uses units.default in Hmisc

units(blood.pressure) <- 'mmHg'

# Specify population model for log odds that Y=1

L <- .4*(sex=='male') + .045*(age-50) +

(log(cholesterol - 10)-5.2)*(-2*(sex=='female') + 2*(sex=='male'))

# Simulate bin

ary y to have Prob(y=1) = 1/[1+exp(-L)]

y <- ifelse(runif(n) < plogis(L), 1, 0)

ddist <- datadist(age, blood.pressure, cholesterol, sex)

fit <- lrm(y ~ blood.pressure + sex * (age + rcs(cholesterol,4)),

```                    x=TRUE, y=TRUE)

```

boundaries <- perimeter(age, cholesterol, lowess=TRUE)

plot(age, cholesterol) # show bivariate data density

lines(boundaries) # and perimeter that will be used for 3-D plot

z <- plot(fit, age=NA, cholesterol=NA, perim=boundaries, method='image')

# draws image() plot

if(!.R.)Legend(z, fun=plogis, at=qlogis(c(.01,.05,.1,.2,.3,.4,.5)), zlab='Probability') # gray scale or color legend for prob.

Ir. Jan Verbesselt
Research Associate
Group of Geomatics Engineering
Department Biosystems ~ Mł-BIORES
Vital Decosterstraat 102, 3000 Leuven, Belgium Tel: +32-16-329750 Fax: +32-16-329760
http://gloveg.kuleuven.ac.be/

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