"""

Classes to support contour plotting and labelling for the Axes class.

"""

from contextlib import ExitStack

import functools

import math

from numbers import Integral

import numpy as np

from numpy import ma

import matplotlib as mpl

from matplotlib import _api, _docstring

from matplotlib.backend_bases import MouseButton

from matplotlib.lines import Line2D

from matplotlib.path import Path

from matplotlib.text import Text

import matplotlib.ticker as ticker

import matplotlib.cm as cm

import matplotlib.colors as mcolors

import matplotlib.collections as mcoll

import matplotlib.font_manager as font_manager

import matplotlib.cbook as cbook

import matplotlib.patches as mpatches

import matplotlib.transforms as mtransforms

from . import artist

def _contour_labeler_event_handler(cs, inline, inline_spacing, event):

canvas = cs.axes.get_figure(root=True).canvas

is_button = event.name == "button_press_event"

is_key = event.name == "key_press_event"

# Quit (even if not in infinite mode; this is consistent with

# MATLAB and sometimes quite useful, but will require the user to

# test how many points were actually returned before using data).

if (is_button and event.button == MouseButton.MIDDLE

or is_key and event.key in ["escape", "enter"]):

canvas.stop_event_loop()

# Pop last click.

elif (is_button and event.button == MouseButton.RIGHT

or is_key and event.key in ["backspace", "delete"]):

# Unfortunately, if one is doing inline labels, then there is currently

# no way to fix the broken contour - once humpty-dumpty is broken, he

# can't be put back together. In inline mode, this does nothing.

if not inline:

cs.pop_label()

canvas.draw()

# Add new click.

elif (is_button and event.button == MouseButton.LEFT

# On macOS/gtk, some keys return None.

or is_key and event.key is not None):

if cs.axes.contains(event)[0]:

cs.add_label_near(event.x, event.y, transform=False,

inline=inline, inline_spacing=inline_spacing)

canvas.draw()

class ContourLabeler:

"""Mixin to provide labelling capability to `.ContourSet`."""

def clabel(self, levels=None, *,

fontsize=None, inline=True, inline_spacing=5, fmt=None,

colors=None, use_clabeltext=False, manual=False,

rightside_up=True, zorder=None):

"""

Label a contour plot.

Adds labels to line contours in this `.ContourSet` (which inherits from

this mixin class).

Parameters

----------

levels : array-like, optional

A list of level values, that should be labeled. The list must be

a subset of ``cs.levels``. If not given, all levels are labeled.

fontsize : str or float, default: :rc:`font.size`

Size in points or relative size e.g., 'small', 'x-large'.

See `.Text.set_size` for accepted string values.

colors : :mpltype:`color` or colors or None, default: None

The label colors:

- If *None*, the color of each label matches the color of

the corresponding contour.

- If one string color, e.g., *colors* = 'r' or *colors* =

'red', all labels will be plotted in this color.

- If a tuple of colors (string, float, RGB, etc), different labels

will be plotted in different colors in the order specified.

inline : bool, default: True

If ``True`` the underlying contour is removed where the label is

placed.

inline_spacing : float, default: 5

Space in pixels to leave on each side of label when placing inline.

This spacing will be exact for labels at locations where the

contour is straight, less so for labels on curved contours.

fmt : `.Formatter` or str or callable or dict, optional

How the levels are formatted:

- If a `.Formatter`, it is used to format all levels at once, using

its `.Formatter.format_ticks` method.

- If a str, it is interpreted as a %-style format string.

- If a callable, it is called with one level at a time and should

return the corresponding label.

- If a dict, it should directly map levels to labels.

The default is to use a standard `.ScalarFormatter`.

manual : bool or iterable, default: False

If ``True``, contour labels will be placed manually using

mouse clicks. Click the first button near a contour to

add a label, click the second button (or potentially both

mouse buttons at once) to finish adding labels. The third

button can be used to remove the last label added, but

only if labels are not inline. Alternatively, the keyboard

can be used to select label locations (enter to end label

placement, delete or backspace act like the third mouse button,

and any other key will select a label location).

*manual* can also be an iterable object of (x, y) tuples.

Contour labels will be created as if mouse is clicked at each

(x, y) position.

rightside_up : bool, default: True

If ``True``, label rotations will always be plus

or minus 90 degrees from level.

use_clabeltext : bool, default: False

If ``True``, use `.Text.set_transform_rotates_text` to ensure that

label rotation is updated whenever the Axes aspect changes.

zorder : float or None, default: ``(2 + contour.get_zorder())``

zorder of the contour labels.

Returns

-------

labels

A list of `.Text` instances for the labels.

"""

# Based on the input arguments, clabel() adds a list of "label

# specific" attributes to the ContourSet object. These attributes are

# all of the form label* and names should be fairly self explanatory.

#

# Once these attributes are set, clabel passes control to the labels()

# method (for automatic label placement) or blocking_input_loop and

# _contour_labeler_event_handler (for manual label placement).

if fmt is None:

fmt = ticker.ScalarFormatter(useOffset=False)

fmt.create_dummy_axis()

self.labelFmt = fmt

self._use_clabeltext = use_clabeltext

self.labelManual = manual

self.rightside_up = rightside_up

self._clabel_zorder = 2 + self.get_zorder() if zorder is None else zorder

if levels is None:

levels = self.levels

indices = list(range(len(self.cvalues)))

else:

levlabs = list(levels)

indices, levels = [], []

for i, lev in enumerate(self.levels):

if lev in levlabs:

indices.append(i)

levels.append(lev)

if len(levels) < len(levlabs):

raise ValueError(f"Specified levels {levlabs} don't match "

f"available levels {self.levels}")

self.labelLevelList = levels

self.labelIndiceList = indices

self._label_font_props = font_manager.FontProperties(size=fontsize)

if colors is None:

self.labelMappable = self

self.labelCValueList = np.take(self.cvalues, self.labelIndiceList)

else:

# handling of explicit colors for labels:

# make labelCValueList contain integers [0, 1, 2, ...] and a cmap

# so that cmap(i) == colors[i]

num_levels = len(self.labelLevelList)

colors = cbook._resize_sequence(mcolors.to_rgba_array(colors), num_levels)

self.labelMappable = cm.ScalarMappable(

cmap=mcolors.ListedColormap(colors), norm=mcolors.NoNorm())

self.labelCValueList = list(range(num_levels))

self.labelXYs = []

if np.iterable(manual):

for x, y in manual:

self.add_label_near(x, y, inline, inline_spacing)

elif manual:

print('Select label locations manually using first mouse button.')

print('End manual selection with second mouse button.')

if not inline:

print('Remove last label by clicking third mouse button.')

mpl._blocking_input.blocking_input_loop(

self.axes.get_figure(root=True),

["button_press_event", "key_press_event"],

timeout=-1, handler=functools.partial(

_contour_labeler_event_handler,

self, inline, inline_spacing))

else:

self.labels(inline, inline_spacing)

return cbook.silent_list('text.Text', self.labelTexts)

def print_label(self, linecontour, labelwidth):

"""Return whether a contour is long enough to hold a label."""

return (len(linecontour) > 10 * labelwidth

or (len(linecontour)

and (np.ptp(linecontour, axis=0) > 1.2 * labelwidth).any()))

def too_close(self, x, y, lw):

"""Return whether a label is already near this location."""

thresh = (1.2 * lw) ** 2

return any((x - loc[0]) ** 2 + (y - loc[1]) ** 2 < thresh

for loc in self.labelXYs)

def _get_nth_label_width(self, nth):

"""Return the width of the *nth* label, in pixels."""

fig = self.axes.get_figure(root=False)

renderer = fig.get_figure(root=True)._get_renderer()

return (Text(0, 0,

self.get_text(self.labelLevelList[nth], self.labelFmt),

figure=fig, fontproperties=self._label_font_props)

.get_window_extent(renderer).width)

def get_text(self, lev, fmt):

"""Get the text of the label."""

if isinstance(lev, str):

return lev

elif isinstance(fmt, dict):

return fmt.get(lev, '%1.3f')

elif callable(getattr(fmt, "format_ticks", None)):

return fmt.format_ticks([*self.labelLevelList, lev])[-1]

elif callable(fmt):

return fmt(lev)

else:

return fmt % lev

def locate_label(self, linecontour, labelwidth):

"""

Find good place to draw a label (relatively flat part of the contour).

"""

ctr_size = len(linecontour)

n_blocks = int(np.ceil(ctr_size / labelwidth)) if labelwidth > 1 else 1

block_size = ctr_size if n_blocks == 1 else int(labelwidth)

# Split contour into blocks of length ``block_size``, filling the last

# block by cycling the contour start (per `np.resize` semantics). (Due

# to cycling, the index returned is taken modulo ctr_size.)

xx = np.resize(linecontour[:, 0], (n_blocks, block_size))

yy = np.resize(linecontour[:, 1], (n_blocks, block_size))

yfirst = yy[:, :1]

ylast = yy[:, -1:]

xfirst = xx[:, :1]

xlast = xx[:, -1:]

s = (yfirst - yy) * (xlast - xfirst) - (xfirst - xx) * (ylast - yfirst)

l = np.hypot(xlast - xfirst, ylast - yfirst)

# Ignore warning that divide by zero throws, as this is a valid option

with np.errstate(divide='ignore', invalid='ignore'):

distances = (abs(s) / l).sum(axis=-1)

# Labels are drawn in the middle of the block (``hbsize``) where the

# contour is the closest (per ``distances``) to a straight line, but

# not `too_close()` to a preexisting label.

hbsize = block_size // 2

adist = np.argsort(distances)

# If all candidates are `too_close()`, go back to the straightest part

# (``adist[0]``).

for idx in np.append(adist, adist[0]):

x, y = xx[idx, hbsize], yy[idx, hbsize]

if not self.too_close(x, y, labelwidth):

break

return x, y, (idx * block_size + hbsize) % ctr_size

def _split_path_and_get_label_rotation(self, path, idx, screen_pos, lw, spacing=5):

"""

Prepare for insertion of a label at index *idx* of *path*.

Parameters

----------

path : Path

The path where the label will be inserted, in data space.

idx : int

The vertex index after which the label will be inserted.

screen_pos : (float, float)

The position where the label will be inserted, in screen space.

lw : float

The label width, in screen space.

spacing : float

Extra spacing around the label, in screen space.

Returns

-------

path : Path

The path, broken so that the label can be drawn over it.

angle : float

The rotation of the label.

Notes

-----

Both tasks are done together to avoid calculating path lengths multiple times,

which is relatively costly.

The method used here involves computing the path length along the contour in

pixel coordinates and then looking (label width / 2) away from central point to

determine rotation and then to break contour if desired. The extra spacing is

taken into account when breaking the path, but not when computing the angle.

"""

xys = path.vertices

codes = path.codes

# Insert a vertex at idx/pos (converting back to data space), if there isn't yet

# a vertex there. With infinite precision one could also always insert the

# extra vertex (it will get masked out by the label below anyways), but floating

# point inaccuracies (the point can have undergone a data->screen->data

# transform loop) can slightly shift the point and e.g. shift the angle computed

# below from exactly zero to nonzero.

pos = self.get_transform().inverted().transform(screen_pos)

if not np.allclose(pos, xys[idx]):

xys = np.insert(xys, idx, pos, axis=0)

codes = np.insert(codes, idx, Path.LINETO)

# Find the connected component where the label will be inserted. Note that a

# path always starts with a MOVETO, and we consider there's an implicit

# MOVETO (closing the last path) at the end.

movetos = (codes == Path.MOVETO).nonzero()[0]

start = movetos[movetos <= idx][-1]

try:

stop = movetos[movetos > idx][0]

except IndexError:

stop = len(codes)

# Restrict ourselves to the connected component.

cc_xys = xys[start:stop]

idx -= start

# If the path is closed, rotate it s.t. it starts at the label.

is_closed_path = codes[stop - 1] == Path.CLOSEPOLY

if is_closed_path:

cc_xys = np.concatenate([cc_xys[idx:-1], cc_xys[:idx+1]])

idx = 0

# Like np.interp, but additionally vectorized over fp.

def interp_vec(x, xp, fp): return [np.interp(x, xp, col) for col in fp.T]

# Use cumulative path lengths ("cpl") as curvilinear coordinate along contour.

screen_xys = self.get_transform().transform(cc_xys)

path_cpls = np.insert(

np.cumsum(np.hypot(*np.diff(screen_xys, axis=0).T)), 0, 0)

path_cpls -= path_cpls[idx]

# Use linear interpolation to get end coordinates of label.

target_cpls = np.array([-lw/2, lw/2])

if is_closed_path: # For closed paths, target from the other end.

target_cpls[0] += (path_cpls[-1] - path_cpls[0])

(sx0, sx1), (sy0, sy1) = interp_vec(target_cpls, path_cpls, screen_xys)

angle = np.rad2deg(np.arctan2(sy1 - sy0, sx1 - sx0)) # Screen space.

if self.rightside_up: # Fix angle so text is never upside-down

angle = (angle + 90) % 180 - 90

target_cpls += [-spacing, +spacing] # Expand range by spacing.

# Get indices near points of interest; use -1 as out of bounds marker.

i0, i1 = np.interp(target_cpls, path_cpls, range(len(path_cpls)),

left=-1, right=-1)

i0 = math.floor(i0)

i1 = math.ceil(i1)

(x0, x1), (y0, y1) = interp_vec(target_cpls, path_cpls, cc_xys)

# Actually break contours (dropping zero-len parts).

new_xy_blocks = []

new_code_blocks = []

if is_closed_path:

if i0 != -1 and i1 != -1:

# This is probably wrong in the case that the entire contour would

# be discarded, but ensures that a valid path is returned and is

# consistent with behavior of mpl <3.8

points = cc_xys[i1:i0+1]

new_xy_blocks.extend([[(x1, y1)], points, [(x0, y0)]])

nlines = len(points) + 1

new_code_blocks.extend([[Path.MOVETO], [Path.LINETO] * nlines])

else:

if i0 != -1:

new_xy_blocks.extend([cc_xys[:i0 + 1], [(x0, y0)]])

new_code_blocks.extend([[Path.MOVETO], [Path.LINETO] * (i0 + 1)])

if i1 != -1:

new_xy_blocks.extend([[(x1, y1)], cc_xys[i1:]])

new_code_blocks.extend([

[Path.MOVETO], [Path.LINETO] * (len(cc_xys) - i1)])

# Back to the full path.

xys = np.concatenate([xys[:start], *new_xy_blocks, xys[stop:]])

codes = np.concatenate([codes[:start], *new_code_blocks, codes[stop:]])

return angle, Path(xys, codes)

def add_label(self, x, y, rotation, lev, cvalue):

"""Add a contour label, respecting whether *use_clabeltext* was set."""

data_x, data_y = self.axes.transData.inverted().transform((x, y))

t = Text(

data_x, data_y,

text=self.get_text(lev, self.labelFmt),

rotation=rotation,

horizontalalignment='center', verticalalignment='center',

zorder=self._clabel_zorder,

color=self.labelMappable.to_rgba(cvalue, alpha=self.get_alpha()),

fontproperties=self._label_font_props,

clip_box=self.axes.bbox)

if self._use_clabeltext:

data_rotation, = self.axes.transData.inverted().transform_angles(

[rotation], [[x, y]])

t.set(rotation=data_rotation, transform_rotates_text=True)

self.labelTexts.append(t)

self.labelCValues.append(cvalue)

self.labelXYs.append((x, y))

# Add label to plot here - useful for manual mode label selection

self.axes.add_artist(t)

def add_label_near(self, x, y, inline=True, inline_spacing=5,

transform=None):

"""

Add a label near the point ``(x, y)``.

Parameters

----------

x, y : float

The approximate location of the label.

inline : bool, default: True

If *True* remove the segment of the contour beneath the label.

inline_spacing : int, default: 5

Space in pixels to leave on each side of label when placing

inline. This spacing will be exact for labels at locations where

the contour is straight, less so for labels on curved contours.

transform : `.Transform` or `False`, default: ``self.axes.transData``

A transform applied to ``(x, y)`` before labeling. The default

causes ``(x, y)`` to be interpreted as data coordinates. `False`

is a synonym for `.IdentityTransform`; i.e. ``(x, y)`` should be

interpreted as display coordinates.

"""

if transform is None:

transform = self.axes.transData

if transform:

x, y = transform.transform((x, y))

idx_level_min, idx_vtx_min, proj = self._find_nearest_contour(

(x, y), self.labelIndiceList)

path = self._paths[idx_level_min]

level = self.labelIndiceList.index(idx_level_min)

label_width = self._get_nth_label_width(level)

rotation, path = self._split_path_and_get_label_rotation(

path, idx_vtx_min, proj, label_width, inline_spacing)

self.add_label(*proj, rotation, self.labelLevelList[idx_level_min],

self.labelCValueList[idx_level_min])

if inline:

self._paths[idx_level_min] = path

def pop_label(self, index=-1):

"""Defaults to removing last label, but any index can be supplied"""

self.labelCValues.pop(index)

t = self.labelTexts.pop(index)

t.remove()

def labels(self, inline, inline_spacing):

for idx, (icon, lev, cvalue) in enumerate(zip(

self.labelIndiceList,

self.labelLevelList,

self.labelCValueList,

)):

trans = self.get_transform()

label_width = self._get_nth_label_width(idx)

additions = []

for subpath in self._paths[icon]._iter_connected_components():

screen_xys = trans.transform(subpath.vertices)

# Check if long enough for a label

if self.print_label(screen_xys, label_width):

x, y, idx = self.locate_label(screen_xys, label_width)

rotation, path = self._split_path_and_get_label_rotation(

subpath, idx, (x, y),

label_width, inline_spacing)

self.add_label(x, y, rotation, lev, cvalue) # Really add label.

if inline: # If inline, add new contours

additions.append(path)

else: # If not adding label, keep old path

additions.append(subpath)

# After looping over all segments on a contour, replace old path by new one

# if inlining.

if inline:

self._paths[icon] = Path.make_compound_path(*additions)

def remove(self):

super().remove()

for text in self.labelTexts:

text.remove()

def _find_closest_point_on_path(xys, p):

"""

Parameters

----------

xys : (N, 2) array-like

Coordinates of vertices.

p : (float, float)

Coordinates of point.

Returns

-------

d2min : float

Minimum square distance of *p* to *xys*.

proj : (float, float)

Projection of *p* onto *xys*.

imin : (int, int)

Consecutive indices of vertices of segment in *xys* where *proj* is.

Segments are considered as including their end-points; i.e. if the

closest point on the path is a node in *xys* with index *i*, this

returns ``(i-1, i)``. For the special case where *xys* is a single

point, this returns ``(0, 0)``.

"""

if len(xys) == 1:

return (((p - xys[0]) ** 2).sum(), xys[0], (0, 0))

dxys = xys[1:] - xys[:-1] # Individual segment vectors.

norms = (dxys ** 2).sum(axis=1)

norms[norms == 0] = 1 # For zero-length segment, replace 0/0 by 0/1.

rel_projs = np.clip( # Project onto each segment in relative 0-1 coords.

((p - xys[:-1]) * dxys).sum(axis=1) / norms,

0, 1)[:, None]

projs = xys[:-1] + rel_projs * dxys # Projs. onto each segment, in (x, y).

d2s = ((projs - p) ** 2).sum(axis=1) # Squared distances.

imin = np.argmin(d2s)

return (d2s[imin], projs[imin], (imin, imin+1))

_docstring.interpd.register(contour_set_attributes=r"""

Attributes

----------

levels : array

The values of the contour levels.

layers : array

Same as levels for line contours; half-way between

levels for filled contours. See ``ContourSet._process_colors``.

""")

@_docstring.interpd

class ContourSet(ContourLabeler, mcoll.Collection):

"""

Store a set of contour lines or filled regions.

User-callable method: `~.Axes.clabel`

Parameters

----------

ax : `~matplotlib.axes.Axes`

levels : [level0, level1, ..., leveln]

A list of floating point numbers indicating the contour levels.

allsegs : [level0segs, level1segs, ...]

List of all the polygon segments for all the *levels*.

For contour lines ``len(allsegs) == len(levels)``, and for

filled contour regions ``len(allsegs) = len(levels)-1``. The lists

should look like ::

level0segs = [polygon0, polygon1, ...]

polygon0 = [[x0, y0], [x1, y1], ...]

allkinds : ``None`` or [level0kinds, level1kinds, ...]

Optional list of all the polygon vertex kinds (code types), as

described and used in Path. This is used to allow multiply-

connected paths such as holes within filled polygons.

If not ``None``, ``len(allkinds) == len(allsegs)``. The lists

should look like ::

level0kinds = [polygon0kinds, ...]

polygon0kinds = [vertexcode0, vertexcode1, ...]

If *allkinds* is not ``None``, usually all polygons for a

particular contour level are grouped together so that

``level0segs = [polygon0]`` and ``level0kinds = [polygon0kinds]``.

**kwargs

Keyword arguments are as described in the docstring of

`~.Axes.contour`.

%(contour_set_attributes)s

"""

def __init__(self, ax, *args,

levels=None, filled=False, linewidths=None, linestyles=None,

hatches=(None,), alpha=None, origin=None, extent=None,

cmap=None, colors=None, norm=None, vmin=None, vmax=None,

colorizer=None, extend='neither', antialiased=None, nchunk=0,

locator=None, transform=None, negative_linestyles=None,

**kwargs):

"""

Draw contour lines or filled regions, depending on

whether keyword arg *filled* is ``False`` (default) or ``True``.

Call signature::

ContourSet(ax, levels, allsegs, [allkinds], **kwargs)

Parameters

----------

ax : `~matplotlib.axes.Axes`

The `~.axes.Axes` object to draw on.

levels : [level0, level1, ..., leveln]

A list of floating point numbers indicating the contour

levels.

allsegs : [level0segs, level1segs, ...]

List of all the polygon segments for all the *levels*.

For contour lines ``len(allsegs) == len(levels)``, and for

filled contour regions ``len(allsegs) = len(levels)-1``. The lists

should look like ::

level0segs = [polygon0, polygon1, ...]

polygon0 = [[x0, y0], [x1, y1], ...]

allkinds : [level0kinds, level1kinds, ...], optional

Optional list of all the polygon vertex kinds (code types), as

described and used in Path. This is used to allow multiply-

connected paths such as holes within filled polygons.

If not ``None``, ``len(allkinds) == len(allsegs)``. The lists

should look like ::

level0kinds = [polygon0kinds, ...]

polygon0kinds = [vertexcode0, vertexcode1, ...]

If *allkinds* is not ``None``, usually all polygons for a

particular contour level are grouped together so that

``level0segs = [polygon0]`` and ``level0kinds = [polygon0kinds]``.

**kwargs

Keyword arguments are as described in the docstring of

`~.Axes.contour`.

"""

if antialiased is None and filled:

# Eliminate artifacts; we are not stroking the boundaries.

antialiased = False

# The default for line contours will be taken from the

# LineCollection default, which uses :rc:`lines.antialiased`.

super().__init__(

antialiaseds=antialiased,

alpha=alpha,

transform=transform,

colorizer=colorizer,

)

self.axes = ax

self.levels = levels

self.filled = filled

self.hatches = hatches

self.origin = origin

self.extent = extent

self.colors = colors

self.extend = extend

self.nchunk = nchunk

self.locator = locator

if "color" in kwargs:

raise _api.kwarg_error("ContourSet.__init__", "color")

if colorizer:

self._set_colorizer_check_keywords(colorizer, cmap=cmap,

norm=norm, vmin=vmin,

vmax=vmax, colors=colors)

norm = colorizer.norm

cmap = colorizer.cmap

if (isinstance(norm, mcolors.LogNorm)

or isinstance(self.locator, ticker.LogLocator)):

self.logscale = True

if norm is None:

norm = mcolors.LogNorm()

else:

self.logscale = False

_api.check_in_list([None, 'lower', 'upper', 'image'], origin=origin)

if self.extent is not None and len(self.extent) != 4:

raise ValueError(

"If given, 'extent' must be None or (x0, x1, y0, y1)")

if self.colors is not None and cmap is not None:

raise ValueError('Either colors or cmap must be None')

if self.origin == 'image':

self.origin = mpl.rcParams['image.origin']

self._orig_linestyles = linestyles # Only kept for user access.

self.negative_linestyles = mpl._val_or_rc(negative_linestyles,

'contour.negative_linestyle')

kwargs = self._process_args(*args, **kwargs)

self._process_levels()

self._extend_min = self.extend in ['min', 'both']

self._extend_max = self.extend in ['max', 'both']

if self.colors is not None:

if mcolors.is_color_like(self.colors):

color_sequence = [self.colors]

else:

color_sequence = self.colors

ncolors = len(self.levels)

if self.filled:

ncolors -= 1

i0 = 0

# Handle the case where colors are given for the extended

# parts of the contour.

use_set_under_over = False

# if we are extending the lower end, and we've been given enough

# colors then skip the first color in the resulting cmap. For the

# extend_max case we don't need to worry about passing more colors

# than ncolors as ListedColormap will clip.

total_levels = (ncolors +

int(self._extend_min) +

int(self._extend_max))

if (len(color_sequence) == total_levels and

(self._extend_min or self._extend_max)):

use_set_under_over = True

if self._extend_min:

i0 = 1

cmap = mcolors.ListedColormap(

cbook._resize_sequence(color_sequence[i0:], ncolors),

under=(color_sequence[0]

if use_set_under_over and self._extend_min else None),

over=(color_sequence[-1]

if use_set_under_over and self._extend_max else None),

)

# label lists must be initialized here

self.labelTexts = []

self.labelCValues = []

self.set_cmap(cmap)

if norm is not None:

self.set_norm(norm)

with self.norm.callbacks.blocked(signal="changed"):

if vmin is not None:

self.norm.vmin = vmin

if vmax is not None:

self.norm.vmax = vmax

self.norm._changed()

self._process_colors()

if self._paths is None:

self._paths = self._make_paths_from_contour_generator()

if self.filled:

if linewidths is not None:

_api.warn_external('linewidths is ignored by contourf')

# Lower and upper contour levels.

lowers, uppers = self._get_lowers_and_uppers()

self.set(edgecolor="none")

else:

self.set(

facecolor="none",

linewidths=self._process_linewidths(linewidths),

linestyle=self._process_linestyles(linestyles),

label="_nolegend_",

# Default zorder taken from LineCollection, which is higher

# than for filled contours so that lines are displayed on top.

zorder=2,

)

self.set(**kwargs) # Let user-set values override defaults.

self.axes.add_collection(self, autolim=False)

self.sticky_edges.x[:] = [self._mins[0], self._maxs[0]]

self.sticky_edges.y[:] = [self._mins[1], self._maxs[1]]

self.axes.update_datalim([self._mins, self._maxs])

self.axes.autoscale_view(tight=True)

self.changed() # set the colors

allsegs = property(lambda self: [

[subp.vertices for subp in p._iter_connected_components()]

for p in self.get_paths()])

allkinds = property(lambda self: [

[subp.codes for subp in p._iter_connected_components()]

for p in self.get_paths()])

alpha = property(lambda self: self.get_alpha())

linestyles = property(lambda self: self._orig_linestyles)

def get_transform(self):

"""Return the `.Transform` instance used by this ContourSet."""

if self._transform is None:

self._transform = self.axes.transData

elif (not isinstance(self._transform, mtransforms.Transform)

and hasattr(self._transform, '_as_mpl_transform')):

self._transform = self._transform._as_mpl_transform(self.axes)

return self._transform

def __getstate__(self):

state = self.__dict__.copy()

# the C object _contour_generator cannot currently be pickled. This

# isn't a big issue as it is not actually used once the contour has

# been calculated.

state['_contour_generator'] = None

return state

def legend_elements(self, variable_name='x', str_format=str):

"""

Return a list of artists and labels suitable for passing through

to `~.Axes.legend` which represent this ContourSet.

The labels have the form "0 < x <= 1" stating the data ranges which

the artists represent.

Parameters

----------

variable_name : str

The string used inside the inequality used on the labels.

str_format : function: float -> str

Function used to format the numbers in the labels.

Returns

-------

artists : list[`.Artist`]

A list of the artists.

labels : list[str]

A list of the labels.

"""

artists = []

labels = []

if self.filled:

lowers, uppers = self._get_lowers_and_uppers()

n_levels = len(self._paths)

for idx in range(n_levels):

artists.append(mpatches.Rectangle(

(0, 0), 1, 1,

facecolor=self.get_facecolor()[idx],

hatch=self.hatches[idx % len(self.hatches)],

))

lower = str_format(lowers[idx])

upper = str_format(uppers[idx])

if idx == 0 and self.extend in ('min', 'both'):

labels.append(fr'${variable_name} \leq {lower}s$')

elif idx == n_levels - 1 and self.extend in ('max', 'both'):

labels.append(fr'${variable_name} > {upper}s$')

else:

labels.append(fr'${lower} < {variable_name} \leq {upper}$')

else:

for idx, level in enumerate(self.levels):

artists.append(Line2D(

[], [],

color=self.get_edgecolor()[idx],

linewidth=self.get_linewidths()[idx],

linestyle=self.get_linestyles()[idx],

))

labels.append(fr'${variable_name} = {str_format(level)}$')

return artists, labels

def _process_args(self, *args, **kwargs):

"""

Process *args* and *kwargs*; override in derived classes.

Must set self.levels, self.zmin and self.zmax, and update Axes limits.

"""

self.levels = args[0]

allsegs = args[1]

allkinds = args[2] if len(args) > 2 else None

self.zmax = np.max(self.levels)

self.zmin = np.min(self.levels)

if allkinds is None:

allkinds = [[None] * len(segs) for segs in allsegs]

# Check lengths of levels and allsegs.

if self.filled:

if len(allsegs) != len(self.levels) - 1:

raise ValueError('must be one less number of segments as '

'levels')

else:

if len(allsegs) != len(self.levels):

raise ValueError('must be same number of segments as levels')

# Check length of allkinds.

if len(allkinds) != len(allsegs):

raise ValueError('allkinds has different length to allsegs')

# Determine x, y bounds and update axes data limits.

flatseglist = [s for seg in allsegs for s in seg]

points = np.concatenate(flatseglist, axis=0)

self._mins = points.min(axis=0)

self._maxs = points.max(axis=0)

# Each entry in (allsegs, allkinds) is a list of (segs, kinds): segs is a list

# of (N, 2) arrays of xy coordinates, kinds is a list of arrays of corresponding

# pathcodes. However, kinds can also be None; in which case all paths in that

# list are codeless (this case is normalized above). These lists are used to

# construct paths, which then get concatenated.

self._paths = [Path.make_compound_path(*map(Path, segs, kinds))

for segs, kinds in zip(allsegs, allkinds)]

return kwargs

def _make_paths_from_contour_generator(self):

"""Compute ``paths`` using C extension."""

if self._paths is not None:

return self._paths

cg = self._contour_generator

empty_path = Path(np.empty((0, 2)))

vertices_and_codes = (

map(cg.create_filled_contour, *self._get_lowers_and_uppers())

if self.filled else

map(cg.create_contour, self.levels))

return [Path(np.concatenate(vs), np.concatenate(cs)) if len(vs) else empty_path

for vs, cs in vertices_and_codes]

def _get_lowers_and_uppers(self):

"""

Return ``(lowers, uppers)`` for filled contours.

"""

lowers = self._levels[:-1]

if self.zmin == lowers[0]:

# Include minimum values in lowest interval

lowers = lowers.copy() # so we don't change self._levels

if self.logscale:

lowers[0] = 0.99 * self.zmin

else:

lowers[0] -= 1

uppers = self._levels[1:]

return (lowers, uppers)

def changed(self):

if not hasattr(self, "cvalues"):

self._process_colors() # Sets cvalues.

# Force an autoscale immediately because self.to_rgba() calls

# autoscale_None() internally with the data passed to it,

# so if vmin/vmax are not set yet, this would override them with

# content from *cvalues* rather than levels like we want

self.norm.autoscale_None(self.levels)

self.set_array(self.cvalues)

self.update_scalarmappable()

alphas = np.broadcast_to(self.get_alpha(), len(self.cvalues))

for label, cv, alpha in zip(self.labelTexts, self.labelCValues, alphas):

label.set_alpha(alpha)

label.set_color(self.labelMappable.to_rgba(cv))

super().changed()

def _ensure_locator_exists(self, N):

"""

Set a locator on this ContourSet if it's not already set.

Parameters

----------

N : int or None

If *N* is an int, it is used as the target number of levels.

Otherwise when *N* is None, a reasonable default is chosen;

for logscales the LogLocator chooses, N=7 is the default

otherwise.

"""

if self.locator is None:

if self.logscale:

self.locator = ticker.LogLocator(numticks=N)

else:

if N is None:

N = 7 # Hard coded default

self.locator = ticker.MaxNLocator(N + 1, min_n_ticks=1)

def _autolev(self):

"""

Select contour levels to span the data.

We need two more levels for filled contours than for

line contours, because for the latter we need to specify

the lower and upper boundary of each range. For example,

a single contour boundary, say at z = 0, requires only

one contour line, but two filled regions, and therefore

three levels to provide boundaries for both regions.

"""

lev = self.locator.tick_values(self.zmin, self.zmax)

try:

if self.locator._symmetric:

return lev

except AttributeError:

pass

# Trim excess levels the locator may have supplied.

under = np.nonzero(lev < self.zmin)[0]

i0 = under[-1] if len(under) else 0

over = np.nonzero(lev > self.zmax)[0]

i1 = over[0] + 1 if len(over) else len(lev)