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Fix geo label side order and prune corner labels #527

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Merged
cvanelteren merged 1 commit into from
Jan 30, 2026
Merged

Fix geo label side order and prune corner labels #527

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127 changes: 125 additions & 2 deletions ultraplot/axes/geo.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@
_BASEMAP_LABEL_Y_SCALE = 0.65 # empirical spacing to mimic cartopy
_BASEMAP_LABEL_X_SCALE = 0.25 # empirical spacing to mimic cartopy
_CARTOPY_LABEL_SIDES = ("labelleft", "labelright", "labelbottom", "labeltop", "geo")
_BASEMAP_LABEL_SIDES = ("labelleft", "labelright", "labeltop", "labelbottom", "geo")
_BASEMAP_LABEL_SIDES = ("labelleft", "labelright", "labelbottom", "labeltop", "geo")


# Format docstring
Expand Down Expand Up @@ -1018,6 +1018,9 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
"""
# Cache of backend-specific gridliner adapters (major/minor).
self._gridliner_adapters: dict[str, _GridlinerAdapter] = {}
# Extra cartopy edge labels (e.g., endpoint longitudes).
self._edge_lon_labels: list[mtext.Text] = []
self._edge_lat_labels: list[mtext.Text] = []
super().__init__(*args, **kwargs)

@override
Expand Down Expand Up @@ -1476,14 +1479,128 @@ def _is_ticklabel_on(self, side: str) -> bool:
return False
return adapter.is_label_on(side)

def _clear_edge_lon_labels(self) -> None:
for label in self._edge_lon_labels:
try:
label.remove()
except Exception:
pass
self._edge_lon_labels = []

def _sync_edge_lon_labels(self) -> None:
"""
Ensure cartopy top longitude labels include the endpoints when requested.
"""
if self._name != "cartopy" or ccrs is None or not self._is_rectilinear():
self._clear_edge_lon_labels()
return
adapter = self._gridliner_adapter("major", create=False)
if adapter is None or not adapter.is_label_on("labeltop"):
self._clear_edge_lon_labels()
return

top_labels = adapter.labels_for_sides(top=True).get("top", [])
if not top_labels:
# No top labels are enabled; avoid adding extras.
self._clear_edge_lon_labels()
return

ticks = np.asarray(self._get_lonticklocs(which="major"))
if ticks.size == 0:
self._clear_edge_lon_labels()
return

# No extra labels; endpoints are intentionally dropped to avoid crowding.
self._clear_edge_lon_labels()

def _clear_edge_lat_labels(self) -> None:
for label in self._edge_lat_labels:
try:
label.remove()
except Exception:
pass
self._edge_lat_labels = []

def _sync_edge_lat_labels(self) -> None:
"""
Ensure cartopy left/right latitude labels include the endpoints when requested.
"""
if self._name != "cartopy" or ccrs is None or not self._is_rectilinear():
self._clear_edge_lat_labels()
return
adapter = self._gridliner_adapter("major", create=False)
if adapter is None:
self._clear_edge_lat_labels()
return

left_on = adapter.is_label_on("labelleft")
right_on = adapter.is_label_on("labelright")
if not left_on and not right_on:
self._clear_edge_lat_labels()
return

left_labels = adapter.labels_for_sides(left=True).get("left", []) if left_on else []
right_labels = adapter.labels_for_sides(right=True).get("right", []) if right_on else []
if not left_labels and not right_labels:
self._clear_edge_lat_labels()
return

ticks = np.asarray(self._get_latticklocs(which="major"))
if ticks.size == 0:
self._clear_edge_lat_labels()
return

# No extra labels; endpoints are intentionally dropped to avoid crowding.
self._clear_edge_lat_labels()

def _prune_corner_labels(self) -> bool:
"""
Drop endpoint labels at the map corners to reduce crowding.
"""
if self._name != "cartopy" or ccrs is None or not self._is_rectilinear():
return False
adapter = self._gridliner_adapter("major", create=False)
if adapter is None:
return False
eps = 1e-6
lon_ticks = np.asarray(self._get_lonticklocs(which="major"))
lat_ticks = np.asarray(self._get_latticklocs(which="major"))
changed = False
if lon_ticks.size:
lon_ends = (lon_ticks[0], lon_ticks[-1])
for side in ("top", "bottom"):
labels = adapter.labels_for_sides(**{side: True}).get(side, [])
for label in labels:
x, _ = label.get_position()
if any(np.isclose(x, end, atol=eps) for end in lon_ends):
if label.get_visible():
label.set_visible(False)
changed = True
if lat_ticks.size:
lat_ends = (lat_ticks[0], lat_ticks[-1])
for side in ("left", "right"):
labels = adapter.labels_for_sides(**{side: True}).get(side, [])
for label in labels:
_, y = label.get_position()
if any(np.isclose(y, end, atol=eps) for end in lat_ends):
if label.get_visible():
label.set_visible(False)
changed = True
return changed

@override
def draw(self, renderer: Any = None, *args: Any, **kwargs: Any) -> None:
# Perform extra post-processing steps
# NOTE: In *principle* axis sharing application step goes here. But should
# already be complete because auto_layout() (called by figure pre-processor)
# has to run it before aligning labels. So this is harmless no-op.
self._apply_axis_sharing()
self._sync_edge_lon_labels()
self._sync_edge_lat_labels()
super().draw(renderer, *args, **kwargs)
# Prune after draw so cartopy has created label artists.
if self._prune_corner_labels():
self.stale = True

def _get_lonticklocs(self, which: str = "major") -> np.ndarray:
"""
Expand Down Expand Up @@ -2692,7 +2809,13 @@ def _update_gridlines(
lonlines = self._get_lonticklocs(which=which)
latlines = self._get_latticklocs(which=which)
if _version_cartopy >= "0.18": # see lukelbd/ultraplot#208
lonlines = (np.asarray(lonlines) + 180) % 360 - 180 # only for cartopy
lonlines = np.asarray(lonlines)
lonlines_mod = (lonlines + 180) % 360 - 180 # only for cartopy
# Preserve distinct -180/180 ticks so both map edges can be labeled.
eps = 1e-10
lonlines_mod = np.where(np.isclose(lonlines, -180), -180 + eps, lonlines_mod)
lonlines_mod = np.where(np.isclose(lonlines, 180), 180 - eps, lonlines_mod)
lonlines = lonlines_mod
gl.xlocator = mticker.FixedLocator(lonlines)
gl.ylocator = mticker.FixedLocator(latlines)
self.stale = True
Expand Down
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