First we plot approval (app) against date (daten). We also specify a few other things. ylim=c(40,80) specifies that the y axis extends from 40 to 80. xlim=c(-3,210) might seem odd, but we need extra space on the left. pch=16 plots dots, and col=”gray” makes them, well, gray.
cex.lab=1.25 and cex.axis=0.75 make the axis labels 1.25 times larger than normal, and the axis value labels 0.75 times normal size. The col.lab = “#777777” makes use of R’s ability to accept hexidecimal color specifications, such as those used by web designers. It’s a very useful function.
I specified that the x-axis label say nothing, while the y-axis label be “Obama job approval (%)”. xaxt=”n”, yaxt=”n” tell R not to plot either the x or y axes.
axis number 1 is the bottom, 2 is the left, etc. All I’m really doing is specifying where the value labels for each axis should be, and what the labels should say, i.e., month abbreviations – “Mar 09” instead of “03/01/09”. The “tck” parameters control the length and direction of the tick marks.