- Base graphics: constructed piecemeal. Conceptually simpler and allows plotting to mirror the thought process.
- Lattice graphics: entire plots created in a simple function call.
- ggplot2 graphics: an implementation of the Grammar of Graphics by Leland Wikinson. Combines concepts from both base and lattice graphics. (Need to install ggplot2 library)
- Fancier and more telling ones.

A list of interactive visualization in R can be found at: http://ouzor.github.io/blog/2014/11/21/interactive-visualizations.html

```
library(datasets)
## scatter plot
plot(x = airquality$Temp, y = airquality$Ozone)
```

```
## par() function is used to specify global graphics parameters that affect all plots in an R session.
## Type ?par to see all parameters
par(mfrow = c(1, 2), mar = c(4, 4, 2, 1), oma = c(0, 0, 2, 0))
with(airquality, {
plot(Wind, Ozone, main="Ozone and Wind")
plot(Temp, Ozone, main="Ozone and Temperature")
mtext("Ozone and Weather in New York City", outer=TRUE)})
```

**PHASE ONE: Mount a canvas panel on the easel, and draw the draft.** (Initialize a plot.)

- plot(): one of the most frequently used plotting functions in R.
- boxplot(): a boxplot show the distribution of a vector. It is very useful to example the distribution of different variables.
- barplot(): create a bar plot with vertical or horizontal bars.
- hist(): compute a histogram of the given data values.
- pie(): draw a pie chart.

Remember to use ?plot or str(plot), etc. to check the arguments when you want to make more personalized plots. A tutorial of base plotting system with more details: http://bcb.dfci.harvard.edu/~aedin/courses/BiocDec2011/2.Plotting.pdf