R: Recipes for Analysis, Visualization and Machine Learning

Visualizing a generalized additive model

In this recipe, we demonstrate how to add a gam fitted regression line to a scatter plot. In addition, we visualize the gam fit using the plot function.

Getting ready

Complete the previous recipe by assigning a gam fitted model to the fit variable.

How to do it...

Perform the following steps to visualize the generalized additive model:

1. Generate a scatter plot using the nox and dis variables:

   > plot(nox, dis)
   

   

   Scatter plot of variable nox against dis

2. Add the regression to the scatter plot:

   > x = seq(0, 1, length = 500)
   > y = predict(fit, data.frame(nox = x))
   > lines(x, y, col = "red", lwd = 2)
   

   Fitted regression of ...