[Matplotlib-users] please document imshow axes order

[Nathan Goldbaum]

Done: https://github.com/matplotlib/matplotlib/pull/14464

btw, you can do stuff like this yourself :)

On Thu, Jun 6, 2019 at 9:43 AM Neal Becker <ndbecker2 at gmail.com> wrote:

> My suggestion is to enhance the documentation.  If there is a nice
> tutorial, adding a link to it would be great.
> Thanks,
> Neal
>
> On Thu, Jun 6, 2019 at 9:39 AM Thomas Caswell <tcaswell at gmail.com> wrote:
> >
> > There is also a tutorial addressing the ways that `origin` and `extent`
> interact with each other:
> https://matplotlib.org/tutorials/intermediate/imshow_extent.html
> >
> > As for the transpose, that is due to one branch of math teaching use to
> think (x, y) and different branch of math teaching us to think (row,
> column).  For `imshow` we use the second one which is consistent with how
> numpy's repr of on array.  It would be confusing if the data for
> `my_array[0, :]` was displayed as the first _column_ of the image.
> >
> > I do not disagree that this is frustrating/confusing, there is a comment
> in some of my grad school code which is basically "getting the (x,y) vs
> (r,c) conversions right here took you an afternoon, don't touch this
> again!" ;)
> >
> > Tom
> >
> > On Thu, Jun 6, 2019 at 9:31 AM Nathan Goldbaum <nathan12343 at gmail.com>
> wrote:
> >>
> >> This is discussed in the description of the "origin" keyword argument:
> >>
> >> origin : {'upper', 'lower'}, optional
> >>
> >> Place the [0,0] index of the array in the upper left or lower left
> corner of the axes. The convention 'upper' is typically used for matrices
> and images. If not given, rcParams["image.origin"] is used, defaulting to
> 'upper'.
> >>
> >> Note that the vertical axes points upward for 'lower' but downward for
> 'upper'.
> >>
> >>
> >> On Thu, Jun 6, 2019 at 9:25 AM Neal Becker <ndbecker2 at gmail.com> wrote:
> >>>
> >>> I just wasted quite a bit of time trying to debug my code.  It took a
> long
> >>> time because I was using imshow to debug, and didn't know that imshow
> >>> displays a matrix not using cartesian coordinates.  The axes are
> transposed
> >>> and one axis is reversed.  The documentation doesn't mention this.
> >>>
> >>> Thanks,
> >>> Neal
> >>>
> >>> _______________________________________________
> >>> Matplotlib-users mailing list
> >>> Matplotlib-users at python.org
> >>> https://mail.python.org/mailman/listinfo/matplotlib-users
> >>
> >> _______________________________________________
> >> Matplotlib-users mailing list
> >> Matplotlib-users at python.org
> >> https://mail.python.org/mailman/listinfo/matplotlib-users
> >
> >
> >
> > --
> > Thomas Caswell
> > tcaswell at gmail.com
>
>
>
> --
> Those who don't understand recursion are doomed to repeat it
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/matplotlib-users/attachments/20190606/35a6c744/attachment.html>