Re: [Matplotlib-users] tick locations in new matshow()

[Eric F. <ef...@ha...>]

Suresh Pillai wrote:
> The new matshow() seems to like ticks every 4 units (or multiples of 4 
> for larger scales) rather than the normal, more desirable every 5 units.
> 
> Compare:
> 
> import pylab
> matrix = pylab.rand(30,30)
> pylab.matshow(matrix)
> pylab.show()
> 
> with
> 
> import pylab
> matrix = pylab.rand(30,30)
> pylab.imshow(matrix)
> pylab.show()
> 
> Looking at the code right now, but since matshow() calls imshow(), it is 
> not obvious to me.  I presume it has something to do with the line
> 
> ax  = fig.add_axes([0.15, 0.09, 0.775, 0.775])
No, this determines where in the figure window the axes will be located.

> 
> in matshow().  Still learning the internals of mpl ...

It is a question of the tick locator that is used.

imshow is using the default MaxNLocator, which generally does a nice job 
but will sometimes put ticks on non-integer locations.  Therefore, for 
matshow, I added a kwarg to guarantee use of integer locations.  I 
should be able to tweak it so that its results differ from the default 
MaxNLocator only when the latter would produce non-integers.  That was 
the intention.

> 
> Also, as mentioned in a previous thread, the new matshow() is missing tick 
> marks on the lower x-axis.

I thought I fixed that in svn, but it looks like I was foiled by a bug 
somewhere in axis.py.  I'll have to track it down.  To be continued...

Eric
> 
> Cheers,
> Suresh