How to see the number of used observations to train a model?

Question

Say I have a linear model in R. Using the model object, how can I see the number of observations used to train that model?

Let say, for instance:

library(ISLR)

lm.fit <- lm(mpg ~ acceleration + weight + horsepower + displacement, data = Auto)

lm.fit

How to see the number of observations used to train the model lm.fit?

Answer 1

For that, you can check the number of fitted values.

length(lm.fit$fitted.values)

# [1] 392

Check:

dim(Auto)

# [1] 392   9

If you are a beginner and want to know more about R then do refer to the following R programming tutorial.