On Tue, Mar 27, 2012 at 3:31 AM, Mike Kaufman <mck...@gmail.com> wrote:
> On 3/26/12 12:49 PM, Christopher Graves wrote:
>
>> On Sun, Mar 11, 2012 at 2:32 PM, Christopher Graves
>> <christoph.gra...@gmail.com <mailto:christoph.gra...@gmail.com>> wrote:
>>
>
> Try this:
>>
>> from pylab import *
>> from matplotlib.ticker import AutoMinorLocator
>>
>> clf()
>> ax=subplot(111)
>> ax.autoscale(tight=True)
>> plot([1,2,4],[1,2,3])
>> ax.xaxis.set_minor_locator(__AutoMinorLocator(2))
>> ax.yaxis.set_minor_locator(__AutoMinorLocator(2))
>>
>> draw()
>>
>> M
>>
>> PS: I believe this is a fairly new feature...
>>
>>
>> Thanks! Great news that AutoMinorLocator has been added and
>> accomplishes this. Regarding the P.S. I can confirm that the feature
>> was not in matplotlib 1.0.1 - I had to update to 1.1.0 to use it.
>>
>> Best /Chris
>>
>>
>>
>> Hi Mike,
>>
>> A follow-up question... When using that, if one then tries to manually
>> use the zoom-box tool available with a matplotlib plot, if one draws too
>> small of a box (less than 2 major ticks in x or y dimension, based on
>> the following error message), it gives the following error and further
>> operations on the plot do not work.
>>
>> ValueError: Need at least two major ticks to find minor tick locations
>> ( File "/usr/lib/pymodules/python2.7/matplotlib/ticker.py", line 1528,
>> in __call__ )
>>
>> Any way to avoid this for now? (And ultimately, should this be made into
>> a bug fix request?)
>>
>
>
> Ok, I seem to remember seeing this error before, but I can't trip it now
> (with either 1.1.1rc or today's git checkout of 1.2.x). Do you have
> a short script that can reproduce this? For me, the zoom-box tool seems to
> be [correctly] setting the majortick locations as I zoom in, thus
> preventing this exception. I should note that I'm using the GTKAgg
> frontend. This may be the issue. A long time ago I was using the MacOSX
> frontend, and maybe this was when I was seeing it...
>
> Aside from that, this would be a bug.
>
> M
>
On Wed, Mar 28, 2012 at 10:50 PM, Christopher Graves <
christoph.gra...@gmail.com> wrote:
> Hi Mike,
>
> Ok I found the root cause. Here is a short script:
>
>
> from pylab import *
>
> from matplotlib.ticker import MultipleLocator, AutoMinorLocator
>
> plot([0,3],[0,2.2])
>
> ax = gca()
>
> ax.xaxis.set_major_locator(MultipleLocator(0.5))
>
> ax.xaxis.set_minor_locator(AutoMinorLocator(2))
>
> show()
>
>
> Once MultipleLocator has been called, the auto-reassigning of tick spacing
> when zooming (either with the zoom box or the cross and right-click drag)
> does not happen, and then AutoMinorLocator has the error because it has
> "majorstep = majorlocs[1] - majorlocs[0]" and majorlocs has less than 2
> elements when zoomed in that far. (GTKAgg vs others doesn't matter.)
>
> Seems like a bug. Is it the same in the newer mpl version you have?
> For my purposes, a different fix could work, because my reason to use
> MultipleLocator is only to make x and y major ticks have equal spacing, as
> follows:
>
> from pylab import *
>
> from matplotlib.ticker import MultipleLocator, AutoMinorLocator
>
> ax = subplot(111, aspect='equal')
>
> plot([0,3],[0,1.1])
>
> # Set the ticks to have the same interval on both x and y axes:
>
> x_major_tick_interval =
> abs(ax.xaxis.get_ticklocs()[0]-ax.xaxis.get_ticklocs()[1])
>
> ax.yaxis.set_major_locator(MultipleLocator(x_major_tick_interval))
>
> # 2 minor ticks per major tick:
>
> ax.yaxis.set_minor_locator(AutoMinorLocator(2))
>
> ax.xaxis.set_minor_locator(AutoMinorLocator(2))
>
> show()
>
>
> aspect='equal' is not necessary to bring out the error, it just
> illustrates the purpose of this. Is there another way to fix the x and y
> tick interval as equal? (And ideally even maintain the equal spacing when
> zooming.. As it is, they initially show as equal, but when zooming they can
> lose equal visible spacing while maintaining equal value intervals.)
>
>
> Best,
>
> Chris
>
On Thu, Mar 29, 2012 at 4:06 AM, Mike Kaufman <mck...@gmail.com> wrote:
> I can confirm this bug on yesterday's checkout. About equal spacing, I
> don't know offhand. A question to ask the list I think. If you could,
> please file as an issue on the github tracker. Include your code nugget
> that reproduces. Thanks.
>
> I don't have a lot of time at this moment, so hopefully somebody else
> looks at fixing it first.
>
> M
>
On Thu, Mar 29, 2012 at 11:53 AM, Christopher Graves <
christoph.gra...@gmail.com> wrote:
>
> Ok, bug is filed at https://github.com/matplotlib/matplotlib/issues/807
>
Has anyone had a chance to take a look at this very annoying bug with using
AutoMinorLocator?
Best,
Chris
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