Class QuiverKey

lib/matplotlib/quiver.py:277–438

Labelled arrow for use as a quiver plot scale key.

class QuiverKey(martist.Artist):
    """Labelled arrow for use as a quiver plot scale key."""
    halign = {'N': 'center', 'S': 'center', 'E': 'left', 'W': 'right'}
    valign = {'N': 'bottom', 'S': 'top', 'E': 'center', 'W': 'center'}
    pivot = {'N': 'middle', 'S': 'middle', 'E': 'tip', 'W': 'tail'}

    def __init__(self, Q, X, Y, U, label,
                 *, angle=0, coordinates='axes', color=None, labelsep=0.1,
                 labelpos='N', labelcolor=None, fontproperties=None,
                 zorder=None, **kwargs):
        """
        Add a key to a quiver plot.

        The positioning of the key depends on *X*, *Y*, *coordinates*, and
        *labelpos*.  If *labelpos* is 'N' or 'S', *X*, *Y* give the position of
        the middle of the key arrow.  If *labelpos* is 'E', *X*, *Y* positions
        the head, and if *labelpos* is 'W', *X*, *Y* positions the tail; in
        either of these two cases, *X*, *Y* is somewhere in the middle of the
        arrow+label key object.

        Parameters
        ----------
        Q : `~matplotlib.quiver.Quiver`
            A `.Quiver` object as returned by a call to `~.Axes.quiver()`.
        X, Y : float
            The location of the key.
        U : float
            The length of the key.
        label : str
            The key label (e.g., length and units of the key).
        angle : float, default: 0
            The angle of the key arrow, in degrees anti-clockwise from the
            horizontal axis.
        coordinates : {'axes', 'figure', 'data', 'inches'}, default: 'axes'
            Coordinate system and units for *X*, *Y*: 'axes' and 'figure' are
            normalized coordinate systems with (0, 0) in the lower left and
            (1, 1) in the upper right; 'data' are the axes data coordinates
            (used for the locations of the vectors in the quiver plot itself);
            'inches' is position in the figure in inches, with (0, 0) at the
            lower left corner.
        color : :mpltype:`color`
            Overrides face and edge colors from *Q*.
        labelpos : {'N', 'S', 'E', 'W'}
            Position the label above, below, to the right, to the left of the
            arrow, respectively.
        labelsep : float, default: 0.1
            Distance in inches between the arrow and the label.
        labelcolor : :mpltype:`color`, default: :rc:`text.color`
            Label color.
        fontproperties : dict, optional
            A dictionary with keyword arguments accepted by the
            `~matplotlib.font_manager.FontProperties` initializer:
            *family*, *style*, *variant*, *size*, *weight*.
        zorder : float
            The zorder of the key. The default is 0.1 above *Q*.
        **kwargs
            Any additional keyword arguments are used to override vector
            properties taken from *Q*.