Thursday, December 5, 2013

Figure width

I had a breakthrough with a figure today. I had made a plot that I really didn't like, and I just couldn't figure out the way to make it better. The answer ended up being that I needed to make the figure narrower.

Tufte talks about data angles and says that data looks best when the majority of the data falls on roughly a 45 degree angle. Obviously, there are many exceptions to this rule, but in my case today, it really helped my figure.

Here is an early version of this figure. The goal is to see how a number of properties at four different locations vary throughout an annual cycle. Some of the cycles can be seen, but overall no clear message from the figure stands out.

Early, wide version of the figure

Here is the updated version of the figure.

Revised, narrow version of the figure. (The height is the same as the older version.)

It is much easier to see how the annual cycles change at the four locations with the narrower figure. Considering, that I only have 12 data points along the x-axis for each variable and position, I did not need such a wide figure. Now, my slopes are also steeper which makes the variability of the annual cycles more obvious. (A lot more data is falling at 45 degree angles like Tufte suggests.)

I made a few other changes too. I care most about the data from 23W and 140W, and I care least about the data from 170W. Therefore, I plotted the least important data in a light gray and the most important data in bold red and black. It's now much easier to differentiate the annual cycles at each position.

If I were to publish this figure, I might remove the gridlines. Are they too much chart clutter? They were, however, helpful today though when I was comparing my results to older published results of similar variables. (A quick note on gridlines: I much prefer my very light gray solid grid lines compared to the matlab default of black dots.)

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