Quick Intro to R Plots

Quick Intro to R Plots

The R language features a rich set of graphical operations both in its base and in advanced packages such as lattice and ggplot2. Here we go through a very brief introduction to base graphics, in this case for bivariate plots.

Open R and paste in the following code:

head(mlb)  # take a look
# separate data frames for pitchers and catchers
mlbc <- mlb[mlb$PosCategory == 'Catcher',] 
mlbp <- mlb[mlb$PosCategory == 'Pitcher',] 
# get mean weights for each height value
meanwtc <- tapply(mlbc$Weight,mlbc$Height,mean) 
meanwtp <- tapply(mlbp$Weight,mlbp$Height,mean) 
# take a look
# get the vector of distinct heights
htsc <- as.numeric(names(meanwtc)) 
htsp <- as.numeric(names(meanwtp)) 
# plot mean wt against ht for pitchers, connected by lines
# add in the catchers

Of course, the calls to plot() and lines() are the only graphical operations here.

We see that catchers tend to be "beefier" than "pitchers," heavier at any given height. Also, height range for pitchers is much broader.