matplotlib.contour

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

class matplotlib.contour.ClabelText(x=0, y=0, text='', color=None, verticalalignment='baseline', horizontalalignment='left', multialignment=None, fontproperties=None, rotation=None, linespacing=None, rotation_mode=None, usetex=None, wrap=False, **kwargs)

Bases: matplotlib.text.Text

Unlike the ordinary text, the get_rotation returns an updated angle in the pixel coordinate assuming that the input rotation is an angle in data coordinate (or whatever transform set).

Create a Text instance at x, y with string text.

Valid keyword arguments are:

Property	Description
agg_filter	a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array
alpha	float or None
animated	bool
backgroundcolor	color
bbox	dict with properties for patches.FancyBboxPatch
clip_box	Bbox
clip_on	bool
clip_path	Patch or (Path, Transform) or None
color or c	color
contains	unknown
figure	Figure
fontfamily or family	{FONTNAME, 'serif', 'sans-serif', 'cursive', 'fantasy', 'monospace'}
fontproperties or font or font_properties	font_manager.FontProperties or str or pathlib.Path
fontsize or size	float or {'xx-small', 'x-small', 'small', 'medium', 'large', 'x-large', 'xx-large'}
fontstretch or stretch	{a numeric value in range 0-1000, 'ultra-condensed', 'extra-condensed', 'condensed', 'semi-condensed', 'normal', 'semi-expanded', 'expanded', 'extra-expanded', 'ultra-expanded'}
fontstyle or style	{'normal', 'italic', 'oblique'}
fontvariant or variant	{'normal', 'small-caps'}
fontweight or weight	{a numeric value in range 0-1000, 'ultralight', 'light', 'normal', 'regular', 'book', 'medium', 'roman', 'semibold', 'demibold', 'demi', 'bold', 'heavy', 'extra bold', 'black'}
gid	str
horizontalalignment or ha	{'center', 'right', 'left'}
in_layout	bool
label	object
linespacing	float (multiple of font size)
multialignment or ma	{'left', 'right', 'center'}
path_effects	AbstractPathEffect
picker	None or bool or callable
position	(float, float)
rasterized	bool or None
rotation	float or {'vertical', 'horizontal'}
rotation_mode	{None, 'default', 'anchor'}
sketch_params	(scale: float, length: float, randomness: float)
snap	bool or None
text	object
transform	Transform
url	str
usetex	bool or None
verticalalignment or va	{'center', 'top', 'bottom', 'baseline', 'center_baseline'}
visible	bool
wrap	bool
x	float
y	float
zorder	float

get_rotation()

Return the text angle in degrees between 0 and 360.

class matplotlib.contour.ContourLabeler

Bases: object

Mixin to provide labelling capability to ContourSet.

add_label(x, y, rotation, lev, cvalue)

Add contour label using Text class.

add_label_clabeltext(x, y, rotation, lev, cvalue)

Add contour label using ClabelText class.

add_label_near(x, y, inline=True, inline_spacing=5, transform=None)

Add a label near the point (x, y). If transform is None (default), (x, y) is in data coordinates; if transform is False, (x, y) is in display coordinates; otherwise, the specified transform will be used to translate (x, y) into display coordinates.

Parameters:

x, yfloat

The approximate location of the label.

inlinebool, default: True

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

inline_spacingint, 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.

calc_label_rot_and_inline(slc, ind, lw, lc=None, spacing=5)

Calculate the appropriate label rotation given the linecontour coordinates in screen units, the index of the label location and the label width.

If lc is not None or empty, also break contours and compute inlining.

spacing is the empty space to leave around the label, in pixels.

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 approximately (label width / 2) away from central point to determine rotation and then to break contour if desired.

clabel(levels=None, *, fontsize=None, inline=True, inline_spacing=5, fmt='%1.3f', 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:

levelsarray-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.

fontsizestr or float, default: rcParams["font.size"] (default: 10.0)

Size in points or relative size e.g., 'smaller', 'x-large'. See Text.set_size for accepted string values.

colorscolor 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.

inlinebool, default: True

If True the underlying contour is removed where the label is placed.

inline_spacingfloat, 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.

fmtstr or dict, default: '%1.3f'

A format string for the label.

Alternatively, this can be a dictionary matching contour levels with arbitrary strings to use for each contour level (i.e., fmt[level]=string), or it can be any callable, such as a Formatter instance, that returns a string when called with a numeric contour level.

manualbool 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_upbool, default: True

If True, label rotations will always be plus or minus 90 degrees from level.

use_clabeltextbool, default: False

If True, ClabelText class (instead of Text) is used to create labels. ClabelText recalculates rotation angles of texts during the drawing time, therefore this can be used if aspect of the axes changes.

zorderfloat or None, default: (2 + contour.get_zorder())

zorder of the contour labels.

Returns:

labels

A list of Text instances for the labels.

get_label_coords(distances, XX, YY, ysize, lw)

Return x, y, and the index of a label location.

Labels are plotted at a location with the smallest deviation of the contour from a straight line unless there is another label nearby, in which case the next best place on the contour is picked up. If all such candidates are rejected, the beginning of the contour is chosen.

get_label_width(lev, fmt, fsize)

Return the width of the label in points.

get_text(lev, fmt)

Get the text of the label.

labels(inline, inline_spacing)

locate_label(linecontour, labelwidth)

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

pop_label(index=- 1)

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

print_label(linecontour, labelwidth)

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

set_label_props(label, text, color)

Set the label properties - color, fontsize, text.

too_close(x, y, lw)

Return True if a label is already near this location.

class matplotlib.contour.ContourSet(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, extend='neither', antialiased=None, nchunk=0, locator=None, transform=None, **kwargs)

Bases: matplotlib.cm.ScalarMappable, matplotlib.contour.ContourLabeler

Store a set of contour lines or filled regions.

User-callable method: clabel

Parameters:

axAxes

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], ...]

allkindsNone 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 contour.

Attributes:

ax

The axes object in which the contours are drawn.

collections

A silent_list of LineCollections or PolyCollections.

levels

Contour levels.

layers

Same as levels for line contours; half-way between levels for filled contours. See _process_colors().

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:

axAxes

The 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 contour.

property ax

changed()

Call this whenever the mappable is changed to notify all the callbackSM listeners to the 'changed' signal.

find_nearest_contour(x, y, indices=None, pixel=True)

Find the point in the contour plot that is closest to (x, y).

Parameters:

x, y: float

The reference point.

indiceslist of int or None, default: None

Indices of contour levels to consider. If None (the default), all levels are considered.

pixelbool, default: True

If True, measure distance in pixel (screen) space, which is useful for manual contour labeling; else, measure distance in axes space.

Returns:

contourCollection

The contour that is closest to (x, y).

segmentint

The index of the Path in contour that is closest to (x, y).

indexint

The index of the path segment in segment that is closest to (x, y).

xmin, yminfloat

The point in the contour plot that is closest to (x, y).

dfloat

The distance from (xmin, ymin) to (x, y).

get_alpha()

Return alpha to be applied to all ContourSet artists.

get_transform()

Return the Transform instance used by this ContourSet.

legend_elements(variable_name='x', str_format=<class 'str'>)

Return a list of artists and labels suitable for passing through to legend which represent this ContourSet.

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

Parameters:

variable_namestr

The string used inside the inequality used on the labels.

str_formatfunction: float -> str

Function used to format the numbers in the labels.

Returns:

artistsList[Artist]

A list of the artists.

labelsList[str]

A list of the labels.

set_alpha(alpha)

Set the alpha blending value for all ContourSet artists. alpha must be between 0 (transparent) and 1 (opaque).

class matplotlib.contour.QuadContourSet(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, extend='neither', antialiased=None, nchunk=0, locator=None, transform=None, **kwargs)

Bases: matplotlib.contour.ContourSet

Create and store a set of contour lines or filled regions.

User-callable method: clabel

Attributes:

ax

The axes object in which the contours are drawn.

collections

A silent_list of LineCollections or PolyCollections.

levels

Contour levels.

layers

Same as levels for line contours; half-way between levels for filled contours. See _process_colors() method.

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:

axAxes

The 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 contour.