matplotlib.quiver.Barbs¶

class
matplotlib.quiver.
Barbs
(ax, *args, pivot='tip', length=7, barbcolor=None, flagcolor=None, sizes=None, fill_empty=False, barb_increments=None, rounding=True, flip_barb=False, **kw)[source]¶ Bases:
matplotlib.collections.PolyCollection
Specialized PolyCollection for barbs.
The only API method is
set_UVC()
, which can be used to change the size, orientation, and color of the arrows. Locations are changed using theset_offsets()
collection method. Possibly this method will be useful in animations.There is one internal function
_find_tails()
which finds exactly what should be put on the barb given the vector magnitude. From there_make_barbs()
is used to find the vertices of the polygon to represent the barb based on this information.Plot a 2D field of barbs.
Call signature:
barbs([X, Y], U, V, [C], **kw)
Where X, Y define the barb locations, U, V define the barb directions, and C optionally sets the color.
All arguments may be 1D or 2D. U, V, C may be masked arrays, but masked X, Y are not supported at present.
Barbs are traditionally used in meteorology as a way to plot the speed and direction of wind observations, but can technically be used to plot any two dimensional vector quantity. As opposed to arrows, which give vector magnitude by the length of the arrow, the barbs give more quantitative information about the vector magnitude by putting slanted lines or a triangle for various increments in magnitude, as show schematically below:
: /\ \ : / \ \ : / \ \ \ : / \ \ \ : 
The largest increment is given by a triangle (or "flag"). After those come full lines (barbs). The smallest increment is a half line. There is only, of course, ever at most 1 half line. If the magnitude is small and only needs a single halfline and no full lines or triangles, the halfline is offset from the end of the barb so that it can be easily distinguished from barbs with a single full line. The magnitude for the barb shown above would nominally be 65, using the standard increments of 50, 10, and 5.
See also https://en.wikipedia.org/wiki/Wind_barb.
Parameters:  X, Y1D or 2D arraylike, optional
The x and y coordinates of the barb locations. See pivot for how the barbs are drawn to the x, y positions.
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 caselen(X)
andlen(Y)
must match the column and row dimensions of U and V. U, V1D or 2D arraylike
The x and y components of the barb shaft.
 C1D or 2D arraylike, optional
Numeric data that defines the barb colors by colormapping via norm and cmap.
This does not support explicit colors. If you want to set colors directly, use barbcolor instead.
 lengthfloat, default: 7
Length of the barb in points; the other parts of the barb are scaled against this.
 pivot{'tip', 'middle'} or float, default: 'tip'
The part of the arrow that is anchored to the X, Y grid. The barb rotates about this point. This can also be a number, which shifts the start of the barb that many points away from grid point.
 barbcolorcolor or color sequence
Specifies the color of all parts of the barb except for the flags. This parameter is analogous to the edgecolor parameter for polygons, which can be used instead. However this parameter will override facecolor.
 flagcolorcolor or color sequence
Specifies the color of any flags on the barb. This parameter is analogous to the facecolor parameter for polygons, which can be used instead. However, this parameter will override facecolor. If this is not set (and C has not either) then flagcolor will be set to match barbcolor so that the barb has a uniform color. If C has been set, flagcolor has no effect.
 sizesdict, optional
A dictionary of coefficients specifying the ratio of a given feature to the length of the barb. Only those values one wishes to override need to be included. These features include:
 'spacing'  space between features (flags, full/half barbs)
 'height'  height (distance from shaft to top) of a flag or full barb
 'width'  width of a flag, twice the width of a full barb
 'emptybarb'  radius of the circle used for low magnitudes
 fill_emptybool, default: False
Whether the empty barbs (circles) that are drawn should be filled with the flag color. If they are not filled, the center is transparent.
 roundingbool, default: True
Whether the vector magnitude should be rounded when allocating barb components. If True, the magnitude is rounded to the nearest multiple of the halfbarb increment. If False, the magnitude is simply truncated to the next lowest multiple.
 barb_incrementsdict, optional
A dictionary of increments specifying values to associate with different parts of the barb. Only those values one wishes to override need to be included.
 'half'  half barbs (Default is 5)
 'full'  full barbs (Default is 10)
 'flag'  flags (default is 50)
 flip_barbbool or arraylike of bool, default: False
Whether the lines and flags should point opposite to normal. Normal behavior is for the barbs and lines to point right (comes from wind barbs having these features point towards low pressure in the Northern Hemisphere).
A single value is applied to all barbs. Individual barbs can be flipped by passing a bool array of the same size as U and V.
Returns:  barbs
Barbs
Other Parameters:  **kwargs
The barbs can further be customized using
PolyCollection
keyword arguments: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 antialiased
or aa or antialiasedsbool or sequence of bools array
ndarray capstyle
{'butt', 'round', 'projecting'} clim
(vmin: float, vmax: float) clip_box
Bbox
clip_on
bool clip_path
Patch or (Path, Transform) or None cmap
colormap or registered colormap name color
color or sequence of rgba tuples contains
callable edgecolor
or ec or edgecolorscolor or sequence of colors or 'face' facecolor
or facecolors or fccolor or sequence of colors figure
Figure
gid
str hatch
{'/', '\', '', '', '+', 'x', 'o', 'O', '.', '*'} in_layout
bool joinstyle
{'miter', 'round', 'bevel'} label
object linestyle
or dashes or linestyles or ls{'', '', '.', ':', '', (offset, onoffseq), ...} linewidth
or linewidths or lwfloat or sequence of floats norm
Normalize
offset_position
{'screen', 'data'} offsets
arraylike (N, 2) or (2,) path_effects
AbstractPathEffect
picker
None or bool or float or callable pickradius
unknown rasterized
bool or None sketch_params
(scale: float, length: float, randomness: float) snap
bool or None transform
Transform
url
str urls
List[str] or None visible
bool zorder
float

barbs_doc
= '\nPlot a 2D field of barbs.\n\nCall signature::\n\n barbs([X, Y], U, V, [C], **kw)\n\nWhere *X*, *Y* define the barb locations, *U*, *V* define the barb\ndirections, and *C* optionally sets the color.\n\nAll arguments may be 1D or 2D. *U*, *V*, *C* may be masked arrays, but masked\n*X*, *Y* are not supported at present.\n\nBarbs are traditionally used in meteorology as a way to plot the speed\nand direction of wind observations, but can technically be used to\nplot any two dimensional vector quantity. As opposed to arrows, which\ngive vector magnitude by the length of the arrow, the barbs give more\nquantitative information about the vector magnitude by putting slanted\nlines or a triangle for various increments in magnitude, as show\nschematically below::\n\n : /\\ \\\n : / \\ \\\n : / \\ \\ \\\n : / \\ \\ \\\n : \n\n\nThe largest increment is given by a triangle (or "flag"). After those\ncome full lines (barbs). The smallest increment is a half line. There\nis only, of course, ever at most 1 half line. If the magnitude is\nsmall and only needs a single halfline and no full lines or\ntriangles, the halfline is offset from the end of the barb so that it\ncan be easily distinguished from barbs with a single full line. The\nmagnitude for the barb shown above would nominally be 65, using the\nstandard increments of 50, 10, and 5.\n\nSee also https://en.wikipedia.org/wiki/Wind_barb.\n\n\n\nParameters\n\nX, Y : 1D or 2D arraylike, optional\n The x and y coordinates of the barb locations. See *pivot* for how the\n barbs are drawn to the x, y positions.\n\n If not given, they will be generated as a uniform integer meshgrid based\n on the dimensions of *U* and *V*.\n\n If *X* and *Y* are 1D but *U*, *V* are 2D, *X*, *Y* are expanded to 2D\n using ``X, Y = np.meshgrid(X, Y)``. In this case ``len(X)`` and ``len(Y)``\n must match the column and row dimensions of *U* and *V*.\n\nU, V : 1D or 2D arraylike\n The x and y components of the barb shaft.\n\nC : 1D or 2D arraylike, optional\n Numeric data that defines the barb colors by colormapping via *norm* and\n *cmap*.\n\n This does not support explicit colors. If you want to set colors directly,\n use *barbcolor* instead.\n\nlength : float, default: 7\n Length of the barb in points; the other parts of the barb\n are scaled against this.\n\npivot : {\'tip\', \'middle\'} or float, default: \'tip\'\n The part of the arrow that is anchored to the *X*, *Y* grid. The barb\n rotates about this point. This can also be a number, which shifts the\n start of the barb that many points away from grid point.\n\nbarbcolor : color or color sequence\n Specifies the color of all parts of the barb except for the flags. This\n parameter is analogous to the *edgecolor* parameter for polygons,\n which can be used instead. However this parameter will override\n facecolor.\n\nflagcolor : color or color sequence\n Specifies the color of any flags on the barb. This parameter is\n analogous to the *facecolor* parameter for polygons, which can be\n used instead. However, this parameter will override facecolor. If\n this is not set (and *C* has not either) then *flagcolor* will be\n set to match *barbcolor* so that the barb has a uniform color. If\n *C* has been set, *flagcolor* has no effect.\n\nsizes : dict, optional\n A dictionary of coefficients specifying the ratio of a given\n feature to the length of the barb. Only those values one wishes to\n override need to be included. These features include:\n\n  \'spacing\'  space between features (flags, full/half barbs)\n  \'height\'  height (distance from shaft to top) of a flag or full barb\n  \'width\'  width of a flag, twice the width of a full barb\n  \'emptybarb\'  radius of the circle used for low magnitudes\n\nfill_empty : bool, default: False\n Whether the empty barbs (circles) that are drawn should be filled with\n the flag color. If they are not filled, the center is transparent.\n\nrounding : bool, default: True\n Whether the vector magnitude should be rounded when allocating barb\n components. If True, the magnitude is rounded to the nearest multiple\n of the halfbarb increment. If False, the magnitude is simply truncated\n to the next lowest multiple.\n\nbarb_increments : dict, optional\n A dictionary of increments specifying values to associate with\n different parts of the barb. Only those values one wishes to\n override need to be included.\n\n  \'half\'  half barbs (Default is 5)\n  \'full\'  full barbs (Default is 10)\n  \'flag\'  flags (default is 50)\n\nflip_barb : bool or arraylike of bool, default: False\n Whether the lines and flags should point opposite to normal.\n Normal behavior is for the barbs and lines to point right (comes from wind\n barbs having these features point towards low pressure in the Northern\n Hemisphere).\n\n A single value is applied to all barbs. Individual barbs can be flipped by\n passing a bool array of the same size as *U* and *V*.\n\nReturns\n\nbarbs : `~matplotlib.quiver.Barbs`\n\nOther Parameters\n\n**kwargs\n The barbs can further be customized using `.PolyCollection` keyword\n arguments:\n\n \n .. table::\n :class: propertytable\n\n ================================================================================================= =====================================================================================================\n Property Description \n ================================================================================================= =====================================================================================================\n :meth:`agg_filter <matplotlib.artist.Artist.set_agg_filter>` a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array\n :meth:`alpha <matplotlib.collections.Collection.set_alpha>` float or None \n :meth:`animated <matplotlib.artist.Artist.set_animated>` bool \n :meth:`antialiased <matplotlib.collections.Collection.set_antialiased>` or aa or antialiaseds bool or sequence of bools \n :meth:`array <matplotlib.cm.ScalarMappable.set_array>` ndarray \n :meth:`capstyle <matplotlib.collections.Collection.set_capstyle>` {\'butt\', \'round\', \'projecting\'} \n :meth:`clim <matplotlib.cm.ScalarMappable.set_clim>` (vmin: float, vmax: float) \n :meth:`clip_box <matplotlib.artist.Artist.set_clip_box>` `.Bbox` \n :meth:`clip_on <matplotlib.artist.Artist.set_clip_on>` bool \n :meth:`clip_path <matplotlib.artist.Artist.set_clip_path>` Patch or (Path, Transform) or None \n :meth:`cmap <matplotlib.cm.ScalarMappable.set_cmap>` colormap or registered colormap name \n :meth:`color <matplotlib.collections.Collection.set_color>` color or sequence of rgba tuples \n :meth:`contains <matplotlib.artist.Artist.set_contains>` callable \n :meth:`edgecolor <matplotlib.collections.Collection.set_edgecolor>` or ec or edgecolors color or sequence of colors or \'face\' \n :meth:`facecolor <matplotlib.collections.Collection.set_facecolor>` or facecolors or fc color or sequence of colors \n :meth:`figure <matplotlib.artist.Artist.set_figure>` `.Figure` \n :meth:`gid <matplotlib.artist.Artist.set_gid>` str \n :meth:`hatch <matplotlib.collections.Collection.set_hatch>` {\'/\', \'\\\\\', \'\', \'\', \'+\', \'x\', \'o\', \'O\', \'.\', \'*\'} \n :meth:`in_layout <matplotlib.artist.Artist.set_in_layout>` bool \n :meth:`joinstyle <matplotlib.collections.Collection.set_joinstyle>` {\'miter\', \'round\', \'bevel\'} \n :meth:`label <matplotlib.artist.Artist.set_label>` object \n :meth:`linestyle <matplotlib.collections.Collection.set_linestyle>` or dashes or linestyles or ls {\'\', \'\', \'.\', \':\', \'\', (offset, onoffseq), ...} \n :meth:`linewidth <matplotlib.collections.Collection.set_linewidth>` or linewidths or lw float or sequence of floats \n :meth:`norm <matplotlib.cm.ScalarMappable.set_norm>` `.Normalize` \n :meth:`offset_position <matplotlib.collections.Collection.set_offset_position>` {\'screen\', \'data\'} \n :meth:`offsets <matplotlib.collections.Collection.set_offsets>` arraylike (N, 2) or (2,) \n :meth:`path_effects <matplotlib.artist.Artist.set_path_effects>` `.AbstractPathEffect` \n :meth:`picker <matplotlib.artist.Artist.set_picker>` None or bool or float or callable \n :meth:`pickradius <matplotlib.collections.Collection.set_pickradius>` unknown \n :meth:`rasterized <matplotlib.artist.Artist.set_rasterized>` bool or None \n :meth:`sketch_params <matplotlib.artist.Artist.set_sketch_params>` (scale: float, length: float, randomness: float) \n :meth:`snap <matplotlib.artist.Artist.set_snap>` bool or None \n :meth:`transform <matplotlib.artist.Artist.set_transform>` `.Transform` \n :meth:`url <matplotlib.artist.Artist.set_url>` str \n :meth:`urls <matplotlib.collections.Collection.set_urls>` List[str] or None \n :meth:`visible <matplotlib.artist.Artist.set_visible>` bool \n :meth:`zorder <matplotlib.artist.Artist.set_zorder>` float \n ================================================================================================= =====================================================================================================\n\n'¶