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Exercise

Using the symbols() function to display relations between more than two variables

The scatterplot allows us to see how one numerical variable changes with the values of a second numerical variable. The symbols() function allows us to extend scatterplots to show the influence of other variables.

This function is called with the variables x and y that define a scatterplot, along with another argument that specifies one of several possible shapes. Here, you are asked to use the circles argument to create a bubbleplot where each data point is represented by a circle whose radius depends on the third variable specified by the value of this argument.

Instructions
100 XP

The Cars93 data frame from the MASS package is already available in your workspace.

  • Use the symbols() function with its default settings and the appropriate arguments to create a bubble plot of MPG.city versus Horsepower from the Cars93 data frame, with the bubble area by the Price variable. Note that this means the bubble radius should be proportional to the square root (sqrt()) of Price.
  • Re-create the first plot, but with the optional argument inches set to 0.1.
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