matplotlib.axes.Axes.fill_between

Axes.fill_between(x, y1, y2=0, where=None, interpolate=False, step=None, *, data=None, **kwargs)[source]

Fill the area between two horizontal curves.

The curves are defined by the points (x, y1) and (x, y2). This creates one or multiple polygons describing the filled area.

You may exclude some horizontal sections from filling using where.

By default, the edges connect the given points directly. Use step if the filling should be a step function, i.e. constant in between x.

Parameters

xarray (length N)

The x coordinates of the nodes defining the curves.

y1array (length N) or scalar

The y coordinates of the nodes defining the first curve.

y2array (length N) or scalar, default: 0

The y coordinates of the nodes defining the second curve.

wherearray of bool (length N), optional

Define where to exclude some horizontal regions from being filled. The filled regions are defined by the coordinates x[where]. More precisely, fill between x[i] and x[i+1] if where[i] and where[i+1]. Note that this definition implies that an isolated True value between two False values in where will not result in filling. Both sides of the True position remain unfilled due to the adjacent False values.

interpolatebool, default: False

This option is only relevant if where is used and the two curves are crossing each other.

Semantically, where is often used for y1 > y2 or similar. By default, the nodes of the polygon defining the filled region will only be placed at the positions in the x array. Such a polygon cannot describe the above semantics close to the intersection. The x-sections containing the intersection are simply clipped.

Setting interpolate to True will calculate the actual intersection point and extend the filled region up to this point.

step{'pre', 'post', 'mid'}, optional

Define step if the filling should be a step function, i.e. constant in between x. The value determines where the step will occur:

• 'pre': The y value is continued constantly to the left from every x position, i.e. the interval (x[i-1], x[i]] has the value y[i].
• 'post': The y value is continued constantly to the right from every x position, i.e. the interval [x[i], x[i+1]) has the value y[i].
• 'mid': Steps occur half-way between the x positions.

Returns

PolyCollection

A PolyCollection containing the plotted polygons.

Other Parameters

dataindexable object, optional

If given, the following parameters also accept a string s, which is interpreted as data[s] (unless this raises an exception):

x, y1, y2, where

**kwargs

All other keyword arguments are passed on to PolyCollection. They control the Polygon properties:

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	array-like or scalar or None
animated	bool
antialiased or aa or antialiaseds	bool or list of bools
array	array-like or None
capstyle	CapStyle or {'butt', 'projecting', 'round'}
clim	(vmin: float, vmax: float)
clip_box	Bbox
clip_on	bool
clip_path	Patch or (Path, Transform) or None
cmap	Colormap or str or None
color	color or list of rgba tuples
edgecolor or ec or edgecolors	color or list of colors or 'face'
facecolor or facecolors or fc	color or list of colors
figure	Figure
gid	str
hatch	{'/', '\', '|', '-', '+', 'x', 'o', 'O', '.', '*'}
in_layout	bool
joinstyle	JoinStyle or {'miter', 'round', 'bevel'}
label	object
linestyle or dashes or linestyles or ls	str or tuple or list thereof
linewidth or linewidths or lw	float or list of floats
norm	Normalize or None
offset_transform	Transform
offsets	(N, 2) or (2,) array-like
path_effects	AbstractPathEffect
paths	list of array-like
picker	None or bool or float or callable
pickradius	float
rasterized	bool
sizes	ndarray or None
sketch_params	(scale: float, length: float, randomness: float)
snap	bool or None
transform	Transform
url	str
urls	list of str or None
verts	list of array-like
verts_and_codes	unknown
visible	bool
zorder	float

See also

fill_between

Fill between two sets of y-values.

fill_betweenx

Fill between two sets of x-values.

Examples using matplotlib.axes.Axes.fill_between