concept lollipop plot in category R

This is an excerpt from Manning's book Exploring Data with R MEAP V05.
Let’s try making another lollipop plot, this time with positive and negative values that will have an effect on the color of the points. We start this off by creating the side column though a mutate() statement. We can either have "negative" or "positive" and those values are factor values. An extra aesthetic is now given to geom_point()’s aes() statement (color = side). We then manually set the colors of the points using scale_color_manual() with values of "blue" and then "red" (representing cold and warm temps). The code for this is available in Listing 11.4 and the lollipop plot itself is in Figure 11.2.