Skip to content

Simplify _init_legend_box. #21289

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 15, 2021
Merged

Simplify _init_legend_box. #21289

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
63 changes: 24 additions & 39 deletions lib/matplotlib/legend.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -712,27 +712,19 @@ def _init_legend_box(self, handles, labels, markerfirst=True):

fontsize = self._fontsize

# legend_box is a HPacker, horizontally packed with
# columns. Each column is a VPacker, vertically packed with
# legend items. Each legend item is HPacker packed with
# legend handleBox and labelBox. handleBox is an instance of
# offsetbox.DrawingArea which contains legend handle. labelBox
# is an instance of offsetbox.TextArea which contains legend
# text.
# legend_box is a HPacker, horizontally packed with columns.
# Each column is a VPacker, vertically packed with legend items.
# Each legend item is a HPacker packed with:
# - handlebox: a DrawingArea which contains the legend handle.
# - labelbox: a TextArea which contains the legend text.

text_list = [] # the list of text instances
handle_list = [] # the list of handle instances
handles_and_labels = []

label_prop = dict(verticalalignment='baseline',
horizontalalignment='left',
fontproperties=self.prop,
)

# The approximate height and descent of text. These values are
# only used for plotting the legend handle.
descent = 0.35 * fontsize * (self.handleheight - 0.7)
# 0.35 and 0.7 are just heuristic numbers and may need to be improved.
descent = 0.35 * fontsize * (self.handleheight - 0.7) # heuristic.
height = fontsize * self.handleheight - descent
# each handle needs to be drawn inside a box of (x, y, w, h) =
# (0, -descent, width, height). And their coordinates should
Expand All @@ -744,7 +736,7 @@ def _init_legend_box(self, handles, labels, markerfirst=True):
# manually set their transform to the self.get_transform().
legend_handler_map = self.get_legend_handler_map()

for orig_handle, lab in zip(handles, labels):
for orig_handle, label in zip(handles, labels):
handler = self.get_legend_handler(legend_handler_map, orig_handle)
if handler is None:
_api.warn_external(
Expand All @@ -753,12 +745,14 @@ def _init_legend_box(self, handles, labels, markerfirst=True):
"https://matplotlib.org/users/legend_guide.html"
"#creating-artists-specifically-for-adding-to-the-legend-"
"aka-proxy-artists".format(orig_handle))
# We don't have a handle for this artist, so we just defer
# to None.
# No handle for this artist, so we just defer to None.
handle_list.append(None)
else:
textbox = TextArea(lab, textprops=label_prop,
multilinebaseline=True)
textbox = TextArea(label, multilinebaseline=True,
textprops=dict(
verticalalignment='baseline',
horizontalalignment='left',
fontproperties=self.prop))
handlebox = DrawingArea(width=self.handlelength * fontsize,
height=height,
xdescent=0., ydescent=descent)
Expand All @@ -770,34 +764,25 @@ def _init_legend_box(self, handles, labels, markerfirst=True):
fontsize, handlebox))
handles_and_labels.append((handlebox, textbox))

if handles_and_labels:
# We calculate number of rows in each column. The first
# (num_largecol) columns will have (nrows+1) rows, and remaining
# (num_smallcol) columns will have (nrows) rows.
ncol = min(self._ncol, len(handles_and_labels))
nrows, num_largecol = divmod(len(handles_and_labels), ncol)
num_smallcol = ncol - num_largecol
# starting index of each column and number of rows in it.
rows_per_col = [nrows + 1] * num_largecol + [nrows] * num_smallcol
start_idxs = np.concatenate([[0], np.cumsum(rows_per_col)[:-1]])
cols = zip(start_idxs, rows_per_col)
else:
cols = []

columnbox = []
for i0, di in cols:
# pack handleBox and labelBox into itemBox
itemBoxes = [HPacker(pad=0,
# array_split splits n handles_and_labels into ncol columns, with the
# first n%ncol columns having an extra entry. filter(len, ...) handles
# the case where n < ncol: the last ncol-n columns are empty and get
# filtered out.
for handles_and_labels_column \
in filter(len, np.array_split(handles_and_labels, self._ncol)):
# pack handlebox and labelbox into itembox
itemboxes = [HPacker(pad=0,
sep=self.handletextpad * fontsize,
children=[h, t] if markerfirst else [t, h],
align="baseline")
for h, t in handles_and_labels[i0:i0 + di]]
# pack columnBox
for h, t in handles_and_labels_column]
# pack columnbox
alignment = "baseline" if markerfirst else "right"
columnbox.append(VPacker(pad=0,
sep=self.labelspacing * fontsize,
align=alignment,
children=itemBoxes))
children=itemboxes))

mode = "expand" if self._mode == "expand" else "fixed"
sep = self.columnspacing * fontsize
Expand Down