Module « matplotlib.pyplot »

Fonction barbs - module matplotlib.pyplot

Signature de la fonction barbs

def barbs(*args, data=None, **kw) 

Description

barbs.__doc__

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 half-line and no full lines or
triangles, the half-line 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, Y : 1D or 2D array-like, 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 case ``len(X)`` and ``len(Y)``
    must match the column and row dimensions of *U* and *V*.

U, V : 1D or 2D array-like
    The x and y components of the barb shaft.

C : 1D or 2D array-like, 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.

length : float, 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.

barbcolor : color or color sequence
    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.

flagcolor : color or color sequence
    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.

sizes : dict, 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_empty : bool, 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.

rounding : bool, 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 half-barb increment.  If False, the magnitude is simply truncated
    to the next lowest multiple.

barb_increments : dict, 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_barb : bool or array-like 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 : `~matplotlib.quiver.Barbs`

Other Parameters
----------------
**kwargs
    The barbs can further be customized using `.PolyCollection` keyword
    arguments:

    Properties:
    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: ndarray 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
    contains: unknown
    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_position: unknown
    offsets: (N, 2) or (2,) array-like
    path_effects: `.AbstractPathEffect`
    picker: None or bool or float or callable
    pickradius: float
    rasterized: bool
    sketch_params: (scale: float, length: float, randomness: float)
    snap: bool or None
    transform: `.Transform`
    url: str
    urls: list of str or None
    visible: bool
    zorder: float

Notes
-----


.. note::
    In addition to the above described arguments, this function can take
    a *data* keyword argument. If such a *data* argument is given,
    every other argument can also be string ``s``, which is
    interpreted as ``data[s]`` (unless this raises an exception).

    Objects passed as **data** must support item access (``data[s]``) and
    membership test (``s in data``).