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Merged
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Aug 13, 2017
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ENH: Switch to a private, simpler AxesStack. #7377

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108 changes: 66 additions & 42 deletions lib/matplotlib/figure.py
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,7 @@ class AxesStack(Stack):

"""
def __init__(self):
cbook.warn_deprecated("2.1")
Stack.__init__(self)
self._ind = 0

Expand Down Expand Up @@ -158,6 +159,62 @@ def __contains__(self, a):
return a in self.as_list()


class _AxesStack(object):
"""Lightweight stack that tracks Axes in a Figure.
"""

def __init__(self):
# We maintain a list of (creation_index, key, axes) tuples.
# We do not use an OrderedDict because 1. the keys may not be hashable
# and 2. we need to directly find a pair corresponding to an axes (i.e.
# we'd really need a two-way dict).
self._items = []
self._created = 0

def as_list(self):
"""Copy of the list of axes, in the order of insertion.
"""
return [ax for _, _, ax in sorted(self._items)]
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I know it's originally sorted this way, but I wonder if that's even necessary...

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The "keep creation order" behavior is mandated by the tests right now, and I don't see a reason to get rid of it.


def get(self, key):
"""Find the axes corresponding to a key; defaults to `None`.
"""
return next((ax for _, k, ax in self._items if k == key), None)
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@anntzer I consistently learn new python details from your code.


def current_key_axes(self):
"""Return the topmost `(key, axes)` pair, or `(None, None)` if empty.
"""
_, key, ax = (self._items or [(None, None, None)])[-1]
return key, ax

def add(self, key, ax):
"""Append a `(key, axes)` pair, unless the axes are already present.
"""
# Skipping existing Axes is needed to support calling `add_axes` with
# an already existing Axes.
if not any(a == ax for _, _, a in self._items):
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This probably needs to handle the duplicate key case?

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@anntzer anntzer Nov 11, 2016 •
edited
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Each call to add is actually preceded by a call to get, so technically we can rely on the caller code to never try to add in a duplicate key. Also I worded the docstring carefully: the pair is not appended if the axes is already present but there's no check on whether the key is :-)

In practice I could make the behavior (no checking for duplicate key) clearer in the docstring, or add a check and error out if the key is already there; either is fine with me. Please let me know your preference.

self._items.append((self._created, key, ax))
self._created += 1

def bubble(self, ax):
"""Move an axes and its corresponding key to the top.
"""
idx, = (idx for idx, (_, _, a) in enumerate(self._items) if a == ax)
self._items.append(self._items[idx])
del self._items[idx]

def remove(self, ax):
"""Remove an axes and its corresponding key.
"""
idx, = (idx for idx, (_, _, a) in enumerate(self._items) if a == ax)
del self._items[idx]

def clear(self):
"""Clear the stack.
"""
del self._items[:]


class SubplotParams(object):
"""
A class to hold the parameters for a subplot
Expand Down Expand Up @@ -358,7 +415,7 @@ def __init__(self,
self.subplotpars = subplotpars
self.set_tight_layout(tight_layout)

self._axstack = AxesStack() # track all figure axes and current axes
self._axstack = _AxesStack() # track all figure axes and current axes
self.clf()
self._cachedRenderer = None

Expand Down Expand Up @@ -410,10 +467,8 @@ def show(self, warn=True):
"matplotlib is currently using a non-GUI backend, "
"so cannot show the figure")

def _get_axes(self):
return self._axstack.as_list()

axes = property(fget=_get_axes, doc="Read-only: list of axes in Figure")
axes = property(lambda self: self._axstack.as_list(),
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Can't this be

    @property
    def axes(self):
        """Read-only: list of axes in Figure"""
        return self._axstack.as_list()

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I don't think one is more readable that the other?

doc="Read-only: list of axes in Figure")

def _get_dpi(self):
return self._dpi
Expand Down Expand Up @@ -835,36 +890,6 @@ def delaxes(self, a):
func(self)
self.stale = True

def _make_key(self, *args, **kwargs):
'make a hashable key out of args and kwargs'

def fixitems(items):
#items may have arrays and lists in them, so convert them
# to tuples for the key
ret = []
for k, v in items:
# some objects can define __getitem__ without being
# iterable and in those cases the conversion to tuples
# will fail. So instead of using the iterable(v) function
# we simply try and convert to a tuple, and proceed if not.
try:
v = tuple(v)
except Exception:
pass
ret.append((k, v))
return tuple(ret)

def fixlist(args):
ret = []
for a in args:
if iterable(a):
a = tuple(a)
ret.append(a)
return tuple(ret)

key = fixlist(args), fixitems(six.iteritems(kwargs))
return key

def add_axes(self, *args, **kwargs):
"""
Add an axes at position *rect* [*left*, *bottom*, *width*,
Expand Down Expand Up @@ -929,9 +954,9 @@ def add_axes(self, *args, **kwargs):

# shortcut the projection "key" modifications later on, if an axes
# with the exact args/kwargs exists, return it immediately.
key = self._make_key(*args, **kwargs)
key = (args, kwargs)
ax = self._axstack.get(key)
if ax is not None:
if ax:
self.sca(ax)
return ax

Expand All @@ -951,7 +976,7 @@ def add_axes(self, *args, **kwargs):
# check that an axes of this type doesn't already exist, if it
# does, set it as active and return it
ax = self._axstack.get(key)
if ax is not None and isinstance(ax, projection_class):
if isinstance(ax, projection_class):
self.sca(ax)
return ax

Expand Down Expand Up @@ -1037,15 +1062,14 @@ def add_subplot(self, *args, **kwargs):
raise ValueError(msg)
# make a key for the subplot (which includes the axes object id
# in the hash)
key = self._make_key(*args, **kwargs)
key = (args, kwargs)
else:
projection_class, kwargs, key = process_projection_requirements(
self, *args, **kwargs)

# try to find the axes with this key in the stack
ax = self._axstack.get(key)

if ax is not None:
if ax:
if isinstance(ax, projection_class):
# the axes already existed, so set it as active & return
self.sca(ax)
Expand Down Expand Up @@ -1614,7 +1638,7 @@ def _gci(self):
do not use elsewhere.
"""
# Look first for an image in the current Axes:
cax = self._axstack.current_key_axes()[1]
ckey, cax = self._axstack.current_key_axes()
if cax is None:
return None
im = cax._gci()
Expand Down
6 changes: 1 addition & 5 deletions lib/matplotlib/projections/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -96,11 +96,7 @@ def process_projection_requirements(figure, *args, **kwargs):
raise TypeError('projection must be a string, None or implement a '
'_as_mpl_axes method. Got %r' % projection)

# Make the key without projection kwargs, this is used as a unique
# lookup for axes instances
key = figure._make_key(*args, **kwargs)

return projection_class, kwargs, key
return projection_class, kwargs, (args, kwargs)


def get_projection_names():
Expand Down