When data is graphed with an offset

Hi there,

I have been subscribed to matplotlib-users before. I have a new job, and now I’m connecting from a new email address. I’ve been using Matplotlib since before 1.0 was released. Currently, I’m using MPL 1.4.2 and Python 3.5 on Ubuntu Linux 15.04 (if any of that matters).

Please have a look at the following graph:

For matplotlib discussion.png

The values in the data set used to plot these two graphs range from 14942 to 14948. In other words, the median of the data set is very far from zero, but the range of the data is very small. With such a data set, MPL subtracts a large offset value from the data points, choosing a value such that the remaining differences are small, positive numbers. I understand the logic behind this, it simplifies graph labeling on the x-axis of the left graph, and the y-axis of the right graph.

However, I do not like the way that MPL is displaying the offset value. It is written in small text, and it does not show up in a consistent place. On a figure with many adjacent axes, it sometimes isn’t clear which axes owns the annotation. I would prefer to incorporate the offset in the axes title: for example, the title of the left graph could read “internal thermistor (+14940)”.

So, what is this offset value called in Matplotlib? How do I retrieve it? How can I override its display? I can obviously do this by wrapping these particular plots in functions which apply the offset before giving the data to MPL. But I would prefer to work with MPL itself, as I don’t always know when MPL will judge that a data offset value is needed.

Thanks for your help!


John J. Ladasky Jr., Ph.D.
Research Scientist

International Technological University

2711 N. First St, San Jose, CA 95134 USA