[R] Question about 'text' (add lm summary to a plot)
Dan Bolser
dmb at mrc-dunn.cam.ac.uk
Thu Jul 21 12:20:24 CEST 2005
I would like to annotate my plot with a little box containing the slope,
intercept and R^2 of a lm on the data.
I would like it to look like...
+----------------------------+
| Slope : 3.45 +- 0.34 |
| Intercept : -10.43 +- 1.42 |
| R^2 : 0.78 |
+----------------------------+
However I can't make anything this neat, and I can't find out how to
combine this with symbols for R^2 / +- (plus minus).
Below is my best attempt (which is franky quite pour). Can anyone
improve on the below?
Specifically,
aligned text and numbers,
aligned decimal places,
symbol for R^2 in the text (expression(R^2) seems to fail with
'paste') and +-
Cheers,
Dan.
dat.lm <- lm(dat$AVG_CH_PAIRS ~ dat$CHAINS)
abline(coef(dat.lm),lty=2,lwd=1.5)
dat.lm.sum <- summary(dat.lm)
dat.lm.sum
attributes(dat.lm.sum)
my.text.1 <-
paste("Slope : ", round(dat.lm.sum$coefficients[2],2),
"+/-", round(dat.lm.sum$coefficients[4],2))
my.text.2 <-
paste("Intercept : ", round(dat.lm.sum$coefficients[1],2),
"+/-", round(dat.lm.sum$coefficients[3],2))
my.text.3 <-
paste("R^2 : ", round(dat.lm.sum$r.squared,2))
my.text.1
my.text.2
my.text.3
## Add legend
text(x=3,
y=300,
paste(my.text.1,
my.text.2,
my.text.3,
sep="\n"),
adj=c(0,0),
cex=1)
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