On Wed, Aug 11, 2010 at 3:11 PM, Benjamin Root <ben.r...@ou.edu> wrote:
> I am tracing down a bug in hist() and I am trying to figure out what is it > about the 'stepfilled' mode that is different from the regular 'bar' mode. > Currently, the hist() code has a separate if branch for dealing with 'step' > and 'stepfilled', and that branch has a bunch of bugs. The best that I can > figure is that it prevents lines from being drawn in between the bins. If > that is the only difference, maybe we could somehow use the bar functions? > > At the very least, I think this needs to be documented better to make it > clear why this oddball approach is happening. > > Thanks, > Ben Root > By the way, the bugs I was referring to both have to do with log=True and the two stepped modes. First, the smallest of values to histogram (the minimum bin value) is, for some reason, used to clip the lower bounds of the histogram count. In some situations, this can result in most if not all the graph not being shown. Second, related to the first is a problem with the 'stepfilled' mode in log space. The stepfilled mode uses the minimum bin value to anchor the patches. However, this can cause the polygon to not close correctly and can get some unsightly artifacts. I have attached an image demonstrating this bug. This has been reported before: http://old.nabble.com/hist%28%29-with-log-and-step-tp28888742p28888742.html http://old.nabble.com/Bug-in-stepfilled-hist-with-log-y-tp28538074p28538074.html In one of the comments, the reporter concluded that it appeared fixed, but either he was experiencing a slightly different problem, or he was mistaken. I have also included a possible patch for addressing these issues. The approach simply sets the minimum value to be zero when not doing log, and use 1.0 when log=True. This differs slightly from how the normal bar graphs are done where a value of 1e-100 is used when log=True, but then the axes limits are adjusted to use 1.0 as a lower limit. Cheers, Ben Root
<<attachment: stepfilledBug.png>>
histlog.patch
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