Note that the scale of x-axis and y-axis is different in your plot. One
simple way to avoid this is to keep the data unit in the x direction is
equal that in the y direction, by setting asp=1 in calling plot function.
X
Dr. Christoph Scherber 写道:
Dear all,
I stumbled over a problem recently when trying to use srt with text() on a
windows device.
What I intended to do was to plot a simple regression line, and to rotate
a piece of text such that the text has the same angle as the regression
line.
However, the text is always plotted in a slightly wrong angle:
####
x=1:10 #create arbitrary x and y values
y=x*2-rnorm(1:10)
plot(x,y,pch=16,xlim=c(0,10)) #create the graph
abline(lm(y~x))
#calculate the y coordinate of the text:
yval=predict(lm(y~x),list(x=rep(2,length(x))))[1]
#calculate the slope:
slope=as.numeric(lm(y~x)[[1]][2])
text(2,yval,"Regression",srt=180/pi*atan(slope),adj=0)
####
What am I doing wrong here?
Many thanks in advance for any help!
Best wishes
Christoph
(using R 2.6.1 on Windows XP)
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and provide commented, minimal, self-contained, reproducible code.
