Using the text() function to label plot features

One of the main uses of the text() function is to add informative labels to a data plot. The text() function takes three arguments:

x, which specifies the value for the x variable,
y, which specifies the value for the y variable, and
label, which specifies the label for the x-y value pair.

This exercise asks you to first create a scatterplot of city gas mileage versus horsepower from the Cars93 data, then identify an interesting subset of the data (i.e. the 3-cylinder cars) and label these points. You will find that assigning a vector to the x, y, and label arguments to text() will result in labeling multiple points at once.

Create a scatterplot of MPG.city vs. Horsepower from the Cars93 data frame, with points represented as solid squares. Recall that the pch value for solid squares is 15.
Create the variable index3 using the which() function that identifies all 3-cylinder cars.
Label the Make of each 3-cylinder car in the Cars93 data frame using the text() function. Use the adj argument to specify left-justified text in your labels.
Use the zoom feature in the Plots window to see this plot more clearly.

Exercise

Using the text() function to label plot features

Instructions