API additions

John,
I think that the problem isn't doing the inversion - it's keeping it. Calling set_xlim() to invert is fine - but it never seems to stay that way. There is a lot of code (resizing, autoscaling, labelling, etc) that has a tendency to flip the axis back to it's 'un-inverted' state. The idea behind having a flag on the axis itself is so that other code can check that easily to see what the state of the axis is.

We do a lot of plots that require an inverted axis and we've had tons of problems keeping the axis inverted (which is where the idea for the flag came from). It seems like people forget that this is possible and add code that assumes that xmin < xmax which then ends up flipping the axis back to it's "normal" state (this happens in the aspect ratio code for example).

Ted

···

At 07:28 AM 10/4/2007, John Hunter wrote:

On 10/4/07, Michael Droettboom <mdroe@...31...> wrote:

> def invert_xaxis(self, invert=True):
>
> "Invert the x-axis if 'invert' is True."
>

I like this approach over a state flag (I agree with Eric that it
would be nice to avoid if we can since it complicates communication
between different parts of the Axes and Axis code). But why do we
need an invert kwarg. I would imagine that invert_xaxis might work
like

def invert_xaxis(self):
    left, right = self.get_xlim()
    self.set_xlim(right, left)

then you could toggle back and forth

and xaxis_inverted would work as you propose.

JDH

-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >> http://get.splunk.com/
_______________________________________________
Matplotlib-devel mailing list
Matplotlib-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-devel

Ted Drain Jet Propulsion Laboratory ted.drain@...179...

I see -- I missed James' original email describing the motivation for
this flag because it was in spam quarantine (I think he posted from a
non-subscribed address). As I was just clearing out the spam, I
noticed it, and now better understand what you are trying to do. It
seems like a reasonable use case.

If I am reading this right, there is no way to support this kind of
behavior *and* not break existing code. If we want to go this route,
I don't mind breaking existing code as long as we do it cleanly. Eg,
I think xmin and xmax should always be in order (calls to
set_xlim(xmax, xmin) would raise a helpful exception like "call
ax.invert_xaxis instead") and we would need to make sure that the
viewlim are still reversed per Michael's request. And we would need a
clean way to toggle back. In this view:

  ax.xaxis_invert() # turns inversion on and off
  ax.get_xlim() # always returns xmin, xmax
  ax.set_xlim(blah) # requires xmin<xmax

and viewlim behave as before.

This would also satisfy Eric's point that xmin and xmax are poorly named.

The one thing I find potentially confusing about Jame's original post
is that set_xlim can be out of order (xmin>xmax) while get_xlim always
returns ordered values.

For the record, I almost never use inverted axes so we should hear
more from those who do....

JDH

···

On 10/4/07, Ted Drain <ted.drain@...179...> wrote:

John,
I think that the problem isn't doing the inversion - it's keeping
it. Calling set_xlim() to invert is fine - but it never seems to
stay that way. There is a lot of code (resizing, autoscaling,
labelling, etc) that has a tendency to flip the axis back to it's
'un-inverted' state. The idea behind having a flag on the axis
itself is so that other code can check that easily to see what the
state of the axis is.

We do a lot of plots that require an inverted axis and we've had tons
of problems keeping the axis inverted (which is where the idea for
the flag came from). It seems like people forget that this is
possible and add code that assumes that xmin < xmax which then ends
up flipping the axis back to it's "normal" state (this happens in the
aspect ratio code for example).

Ted Drain wrote:

John,
I think that the problem isn't doing the inversion - it's keeping it. Calling set_xlim() to invert is fine - but it never seems to stay that way. There is a lot of code (resizing, autoscaling, labelling, etc) that has a tendency to flip the axis back to it's 'un-inverted' state. The idea behind having a flag on the axis itself is so that other code can check that easily to see what the state of the axis is.

We do a lot of plots that require an inverted axis and we've had tons of problems keeping the axis inverted (which is where the idea for the flag came from). It seems like people forget that this is possible and add code that assumes that xmin < xmax which then ends up flipping the axis back to it's "normal" state (this happens in the aspect ratio code for example).

OK, I found an example with set_aspect(2, adjustable='datalim').

I would still like to see as many specific examples as you can provide.

Eric

···

Ted