matplotlib.pyplot.quiver#

matplotlib.pyplot.quiver(*args, data=None, **kwargs)[source]#

Plot a 2D field of arrows.

Call signature:

quiver([X, Y], U, V, [C], **kwargs)

X, Y define the arrow locations, U, V define the arrow directions, and C optionally sets the color.

Arrow length

The default settings auto-scales the length of the arrows to a reasonable size. To change this behavior see the scale and scale_units parameters.

Arrow shape

The arrow shape is determined by width, headwidth, headlength and headaxislength. See the notes below.

Arrow styling

Each arrow is internally represented by a filled polygon with a default edge linewidth of 0. As a result, an arrow is rather a filled area, not a line with a head, and PolyCollection properties like linewidth, edgecolor, facecolor, etc. act accordingly.

Parameters:

X, Y1D or 2D array-like, optional

The x and y coordinates of the arrow locations.

If not given, they will be generated as a uniform integer meshgrid based on the dimensions of U and V.

If X and Y are 1D but U, V are 2D, X, Y are expanded to 2D using X, Y = np.meshgrid(X, Y). In this case len(X) and len(Y) must match the column and row dimensions of U and V.

U, V1D or 2D array-like

The x and y direction components of the arrow vectors. The interpretation of these components (in data or in screen space) depends on angles.

U and V must have the same number of elements, matching the number of arrow locations in X, Y. U and V may be masked. Locations masked in any of U, V, and C will not be drawn.

C1D or 2D array-like, optional

Numeric data that defines the arrow colors by colormapping via norm and cmap.

This does not support explicit colors. If you want to set colors directly, use color instead. The size of C must match the number of arrow locations.

angles{'uv', 'xy'} or array-like, default: 'uv'

Method for determining the angle of the arrows.

'uv': Arrow direction in screen coordinates. Use this if the arrows symbolize a quantity that is not based on X, Y data coordinates.

If U == V the orientation of the arrow on the plot is 45 degrees counter-clockwise from the horizontal axis (positive to the right).
'xy': Arrow direction in data coordinates, i.e. the arrows point from (x, y) to (x+u, y+v). Use this e.g. for plotting a gradient field.
Arbitrary angles may be specified explicitly as an array of values in degrees, counter-clockwise from the horizontal axis.

In this case U, V is only used to determine the length of the arrows.

Note: inverting a data axis will correspondingly invert the arrows only with angles='xy'.

pivot{'tail', 'mid', 'middle', 'tip'}, default: 'tail'

The part of the arrow that is anchored to the X, Y grid. The arrow rotates about this point.

'mid' is a synonym for 'middle'.

scalefloat, optional

Scales the length of the arrow inversely.

Number of data units per arrow length unit, e.g., m/s per plot width; a smaller scale parameter makes the arrow longer. Default is None.

If None, a simple autoscaling algorithm is used, based on the average vector length and the number of vectors. The arrow length unit is given by the scale_units parameter.

scale_units{'width', 'height', 'dots', 'inches', 'x', 'y', 'xy'}, optional

If the scale kwarg is None, the arrow length unit. Default is None.

e.g. scale_units is 'inches', scale is 2.0, and (u, v) = (1, 0), then the vector will be 0.5 inches long.

If scale_units is 'width' or 'height', then the vector will be half the width/height of the axes.

If scale_units is 'x' then the vector will be 0.5 x-axis units. To plot vectors in the x-y plane, with u and v having the same units as x and y, use angles='xy', scale_units='xy', scale=1.

units{'width', 'height', 'dots', 'inches', 'x', 'y', 'xy'}, default: 'width'

Affects the arrow size (except for the length). In particular, the shaft width is measured in multiples of this unit.

Supported values are:

'width', 'height': The width or height of the Axes.
'dots', 'inches': Pixels or inches based on the figure dpi.
'x', 'y', 'xy': X, Y or \(\sqrt{X^2 + Y^2}\) in data units.

The following table summarizes how these values affect the visible arrow size under zooming and figure size changes:

units	zoom	figure size change
'x', 'y', 'xy'	arrow size scales
'width', 'height'		arrow size scales
'dots', 'inches'

widthfloat, optional

Shaft width in arrow units. All head parameters are relative to width.

The default depends on choice of units above, and number of vectors; a typical starting value is about 0.005 times the width of the plot.

headwidthfloat, default: 3

Head width as multiple of shaft width. See the notes below.

headlengthfloat, default: 5

Head length as multiple of shaft width. See the notes below.

headaxislengthfloat, default: 4.5

Head length at shaft intersection as multiple of shaft width. See the notes below.

minshaftfloat, default: 1

Length below which arrow scales, in units of head length. Do not set this to less than 1, or small arrows will look terrible!

minlengthfloat, default: 1

Minimum length as a multiple of shaft width; if an arrow length is less than this, plot a dot (hexagon) of this diameter instead.

colorcolor or color sequence, optional

Explicit color(s) for the arrows. If C has been set, color has no effect.

This is a synonym for the PolyCollection facecolor parameter.

Returns:

Quiver

Other Parameters:

dataindexable object, optional

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

**kwargsPolyCollection properties, optional

All other keyword arguments are passed on to PolyCollection:

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 and two offsets from the bottom left corner of the image
`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
`mouseover`	bool
`norm`	`Normalize` or str or None
`offset_transform` or transOffset	unknown
`offsets`	(N, 2) or (2,) array-like
`path_effects`	`AbstractPathEffect`
`paths`	list of array-like
`picker`	None or bool or float or callable
`pickradius`	unknown
`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