Re: [Matplotlib-users] ordinal must be >= 1 Error

[John H. <jdh...@ac...>]

>>>>> "Panos" == Panos Kassianidis <pk...@in...> writes:

    Panos> Hello all, I am using matplotlib for a web application to
    Panos> create trend charts from measurements stored in a database.
    Panos> Specifically I use plot_date to plot the values vs their
    Panos> timestamps.  Occasionally and without any obvious to me
    Panos> reason, plot_date raises the exception

    Panos> "ordinal must be >= 1"

    Panos> I check that both the x and y value sequences are not empty
    Panos> and their length is certainly above 1.  Does anybody know
    Panos> where this "ordinal" refers to and what might be causing
    Panos> this error?  Thank you very much

I sometimes see this when a date graph is open in a GUI window and I
am moving my mouse.  The mouse as is passes off the axes can return
invalid dates to the matplotlib date conversion routine.  I think I
added some guards against this in the last release (0.86.2).  What
version are you using.

In a nutshell, it likely means that somewhere in the pipeline
matplotlib is getting an illegal date value.

Next time you get the error, lease post version info and a complete
traceback.

JDH