Thraupidae - 6 months ago 48

R Question

Using R, I would like to plot a linear relationship between two variables, but I would like the fitted line to be present only within the range of the data.

For example, if I have the following code, I would like the line to exist only from x and y values of 1:10 (with default parameters this line extends beyond the range of data points).

`x <- 1:10`

y <- 1:10

plot(x,y)

abline(lm(y~x))

Answer

Instead of using `abline()`

, (a) save the fitted model, (b) use `predict.lm()`

to find the fitted y-values corresponding to x=1 and x=10, and then (c) use `lines()`

to add a line between the two points:

```
f <- lm(y~x)
X <- c(1, 10)
Y <- predict(f, newdata=data.frame(x=X))
plot(x,y)
lines(x=X, y=Y)
```