Chapter 6. Decorations

Data alone doesn’t tell a story. To be useful, the data needs to be placed into context: at least, we must tell the observer what the data is (such as position versus time, particle count versus scattering angle, stock price versus date, or whatever) and what units the data is plotted in (centimeters or inches, seconds or minutes, dollars or euros). No plot is complete without this information.

But we can do much more to make a graph useful and informative: we can add arrows and annotations on the graph to point out and explain interesting features. We may also want to provide special tic marks and labels to make quantitative information stand out more. Or we may need to change the overall size and shape of the entire graph to accommodate a specific data set.

In this chapter, we discuss all the means that gnuplot offers to put additional information on a plot (in addition to the actual data). Because much of this material is quite dry, I’ve gathered the most important commands and options together in the next section. Unless you have special needs, this may be all you need to know right now—gnuplot is quite good at automatically “doing the right thing” in most situations.

6.1. Quick start: minimal context for data

6.2. Digression: locations on a graph

6.3. Additional graph elements: decorations

6.4. The graph’s legend or key

6.5. Worked example: features of a spectrum

6.6. Overall appearance

6.7. Summary