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Tick rendering speedups #29394

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Tick rendering speedups #29394

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22 changes: 14 additions & 8 deletions lib/matplotlib/axis.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1269,7 +1269,7 @@ def _set_artist_props(self, a):
def _update_ticks(self):
"""
Update ticks (position and labels) using the current data interval of
the axes. Return the list of ticks that will be drawn.
the axes.
"""
major_locs = self.get_majorticklocs()
major_labels = self.major.formatter.format_ticks(major_locs)
Expand All @@ -1285,7 +1285,7 @@ def _update_ticks(self):
tick.update_position(loc)
tick.label1.set_text(label)
tick.label2.set_text(label)
ticks = [*major_ticks, *minor_ticks]
self._ticks = [*major_ticks, *minor_ticks]
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I‘m somewhat skeptical this is a good idea. It’s essentially a caching mechanism for the expensive (?) lookup of the current ticks. This adds more state and makes tick handling more complicated.

On a general note. The fundamental problem is the tick design:

  • Ticks consist of three Line2D objects and two Text objects. This is heavy.
  • Ticks are often created / modified.

This combination makes Ticks expensive. One mitigation strategy we use is that ticks are repurposed instead of being recreated - this is the update_ticks mechanism. The second trick is the lazy behavior of tick lists. Ticks are only created when you need them first. Overall these are still only bandaids on the fundamentally expensive tick design. And the change here goes into the same category.

I believe to substantially improve performance, we have to move away from heavy Tick instances and loops over then. See #5665 (comment). Alternatively/complementary, ticks could get more lightweight with a borg-like pattern.

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@scottshambaugh scottshambaugh Jan 2, 2025 •
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I agree with your assessment on Ticks being heavy, and a refactor being the real solution here. The highlighted branch of the call tree here shows the ticks taking up well over half the time associated with the figure & 3d axes creation and drawing.

Screenshot 2025-01-01 180309

Think the extra state isn't worth the ~20% speedup? I don't feel too strongly either way.

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I‘d like to put this on hold. I plan to pick up the refactoring plan soon, and this additional state would complicate that. We might put the caching then behind the TickCollection abstraction.

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Sounds good to me!


view_low, view_high = self.get_view_interval()
if view_low > view_high:
Expand All @@ -1302,18 +1302,24 @@ def _update_ticks(self):
view_high = view_high - delta * margin
view_low = view_low + delta * margin

interval_t = self.get_transform().transform([view_low, view_high])
self._interval_t = self.get_transform().transform([view_low, view_high])

def _get_ticks_to_draw(self, update=True):
"""
Return the list of ticks that will be drawn.
"""
if update:
self._update_ticks()
ticks_to_draw = []
for tick in ticks:
for tick in self._ticks:
try:
loc_t = self.get_transform().transform(tick.get_loc())
except AssertionError:
# transforms.transform doesn't allow masked values but
# some scales might make them, so we need this try/except.
pass
else:
if mtransforms._interval_contains_close(interval_t, loc_t):
if mtransforms._interval_contains_close(self._interval_t, loc_t):
ticks_to_draw.append(tick)

return ticks_to_draw
Expand Down Expand Up @@ -1341,7 +1347,7 @@ def get_tightbbox(self, renderer=None, *, for_layout_only=False):
return
if renderer is None:
renderer = self.get_figure(root=True)._get_renderer()
ticks_to_draw = self._update_ticks()
ticks_to_draw = self._get_ticks_to_draw(update=True)

self._update_label_position(renderer)

Expand Down Expand Up @@ -1394,7 +1400,7 @@ def draw(self, renderer):
return
renderer.open_group(__name__, gid=self.get_gid())

ticks_to_draw = self._update_ticks()
ticks_to_draw = self._get_ticks_to_draw(update=True)
tlb1, tlb2 = self._get_ticklabel_bboxes(ticks_to_draw, renderer)

for tick in ticks_to_draw:
Expand Down Expand Up @@ -2230,7 +2236,7 @@ def _get_tick_boxes_siblings(self, renderer):
# If we want to align labels from other Axes:
for ax in grouper.get_siblings(self.axes):
axis = ax._axis_map[name]
ticks_to_draw = axis._update_ticks()
ticks_to_draw = axis._get_ticks_to_draw(update=True)
tlb, tlb2 = axis._get_ticklabel_bboxes(ticks_to_draw, renderer)
bboxes.extend(tlb)
bboxes2.extend(tlb2)
Expand Down
2 changes: 1 addition & 1 deletion lib/matplotlib/spines.py
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Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ def get_window_extent(self, renderer=None):
if self.axis is None or not self.axis.get_visible():
return bb
bboxes = [bb]
drawn_ticks = self.axis._update_ticks()
drawn_ticks = self.axis._get_ticks_to_draw(update=True)

major_tick = next(iter({*drawn_ticks} & {*self.axis.majorTicks}), None)
minor_tick = next(iter({*drawn_ticks} & {*self.axis.minorTicks}), None)
Expand Down
3 changes: 2 additions & 1 deletion lib/matplotlib/tests/test_axes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3128,7 +3128,8 @@ def test_log_scales():
ax.invert_yaxis()
ax.set_xscale('log', base=9.0)
xticks, yticks = (
[(t.get_loc(), t.label1.get_text()) for t in axis._update_ticks()]
[(t.get_loc(), t.label1.get_text())
for t in axis._get_ticks_to_draw(update=True)]
for axis in [ax.xaxis, ax.yaxis]
)
assert xticks == [
Expand Down
3 changes: 3 additions & 0 deletions lib/mpl_toolkits/mplot3d/axes3d.py
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Original file line number Diff line number Diff line change
Expand Up @@ -456,6 +456,9 @@ def draw(self, renderer):
artist.do_3d_projection()

if self._axis3don:
# Update ticks
for axis in self._axis_map.values():
axis._update_ticks()
# Draw panes first
for axis in self._axis_map.values():
axis.draw_pane(renderer)
Expand Down
34 changes: 22 additions & 12 deletions lib/mpl_toolkits/mplot3d/axis3d.py
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Original file line number Diff line number Diff line change
Expand Up @@ -435,10 +435,9 @@ def _axmask(self):

def _draw_ticks(self, renderer, edgep1, centers, deltas, highs,
deltas_per_point, pos):
ticks = self._update_ticks()
ticks = self._get_ticks_to_draw(update=False) # We updated in Axes3D.draw()
info = self._axinfo
index = info["i"]
juggled = info["juggled"]

mins, maxs, tc, highs = self._get_coord_info()
centers, deltas = self._calc_centers_deltas(maxs, mins)
Expand All @@ -461,17 +460,28 @@ def _draw_ticks(self, renderer, edgep1, centers, deltas, highs,
# Get tick line positions
pos = edgep1.copy()
pos[index] = tick.get_loc()
pos[tickdir] = out_tickdir
x1, y1, z1 = proj3d.proj_transform(*pos, self.axes.M)
pos[tickdir] = in_tickdir
x2, y2, z2 = proj3d.proj_transform(*pos, self.axes.M)

# Get position of label
labeldeltas = (tick.get_pad() + default_label_offset) * points
# Add out and in tickdir positions
positions = []
for td in (out_tickdir, in_tickdir):
p = pos.copy()
p[tickdir] = td
positions.append(p)

# Add label position
p = pos.copy()
p[tickdir] = edgep1_tickdir
positions.append(_move_from_center(
p, centers,
(tick.get_pad() + default_label_offset) * points,
self._axmask()
))

xs, ys, zs = proj3d._proj_trans_points(np.array(positions), self.axes.M)

pos[tickdir] = edgep1_tickdir
pos = _move_from_center(pos, centers, labeldeltas, self._axmask())
lx, ly, lz = proj3d.proj_transform(*pos, self.axes.M)
x1, y1, z1 = xs[0], ys[0], zs[0]
x2, y2, z2 = xs[1], ys[1], zs[1]
lx, ly, lz = xs[2], ys[2], zs[2]

_tick_update_position(tick, (x1, x2), (y1, y2), (lx, ly))
tick.tick1line.set_linewidth(tick_lw[tick._major])
Expand Down Expand Up @@ -636,7 +646,7 @@ def draw_grid(self, renderer):

renderer.open_group("grid3d", gid=self.get_gid())

ticks = self._update_ticks()
ticks = self._get_ticks_to_draw(update=False) # We updated in Axes3D.draw()
if len(ticks):
# Get general axis information:
info = self._axinfo
Expand Down
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