Jim Horning wrote:
> Greetings,
>
> I've been having difficulties with axis limit control. From a bigger
> application I've reduced an example down to the following short code
> segment. Note, the commented-out line, #x = numpy.linspace(98.42,
> 99.21, 100), line in which the example works OKAY.
>
> What is annoying is that the following example will produce a graph in
> which the x-axis is labeled at ticks starting at 0.1 going to 0.35
> (times 1.474e2 !) Instead, I am expecting an axis from 147.63 to
> 148.31. Note that if you swap out the x with the commented-out line
> the example works like I would expect.
First, a small bug in your example. I think you meant:
pylab.xlim(numpy.min(x), numpy.min(x))
to be:
pylab.xlim(numpy.min(x), numpy.max(x))
In the former case, when you have "unity" limits, matplotlib adds a
small delta to the min and max so the range is not empty.
Once this is fixed, the notation is actually ~0.1 to ~0.8 *plus* (not
*times*) 1.474e2, which is at least correct, if not desired. The reason
matplotlib does this is that, for space considerations, it avoids
displaying ticks with more than 4 significant digits. Since the range
here is so small, it prints the "offset" in the lower right and adjusts
the ticks accordingly. Unfortunately, this number of significant digits
isn't user customizable, though perhaps it should be (just as the range
for scientific notation is). Can you file an enhancement request in the
tracker so this doesn't get lost?
Does anyone with more experience with the scientific notation/offset
code have any further comments?
Mike
>
> By the way, this example is with pylab. However, I've got the same
> problem using plt from matplotlib or anything matplotlib related.
> ===
>
> import random
> import numpy
> import pylab
>
> #x = numpy.linspace(98.42, 99.21, 100)
> x = numpy.linspace(147.63, 148.31, 100)
> y = numpy.random.random((len(x)))
> pylab.plot(x, y)
> pylab.xlim(numpy.min(x), numpy.min(x))
> pylab.show()
>
>
> --
> --------------------
> Jim A. Horning
> ji...@ji... <mailto:ji...@ji...>
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--
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA