I’m plotting upper and lower limits via the lolims and uplims keywords to the errorbar function and have noticed two problems.

First, the direction of the arrows produced by these keywords are opposite to one would expect, i.e. lolims=True should produce an upward-pointing arrow and uplims should produce a downward-pointing arrow. For example, a “lower-limit” means the exact value is unknown, but it is known not to be below a particular value – this is denoted by an upward arrow whose starting point (arrow base) is at the value of the lower limit. The xlolims and yuplims have this similar reversed behavior.

The second point deals with the starting point of the arrow base. For limits, the arrow should begin at the value of upper/lower limit. Currently the arrows are centered at the limit value.

To summarize both issues with an example:

errorbar(10, 10, yerr=1, uplims=True) should produce a downward pointing arrow whose base is at (10, 10) and whose head is at (10, 9). It currently produces an upward-pointing arrow whose base is at (10,9) and whose head is at (10, 11).

Thanks,

Larry