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Fonction legend - module matplotlib.pyplot

Signature de la fonction legend

def legend(*args, **kwargs) 

Description

legend.__doc__

Place a legend on the Axes.

Call signatures::

    legend()
    legend(labels)
    legend(handles, labels)

The call signatures correspond to these three different ways to use
this method:

**1. Automatic detection of elements to be shown in the legend**

The elements to be added to the legend are automatically determined,
when you do not pass in any extra arguments.

In this case, the labels are taken from the artist. You can specify
them either at artist creation or by calling the
:meth:`~.Artist.set_label` method on the artist::

    ax.plot([1, 2, 3], label='Inline label')
    ax.legend()

or::

    line, = ax.plot([1, 2, 3])
    line.set_label('Label via method')
    ax.legend()

Specific lines can be excluded from the automatic legend element
selection by defining a label starting with an underscore.
This is default for all artists, so calling `.Axes.legend` without
any arguments and without setting the labels manually will result in
no legend being drawn.


**2. Labeling existing plot elements**

To make a legend for lines which already exist on the Axes
(via plot for instance), simply call this function with an iterable
of strings, one for each legend item. For example::

    ax.plot([1, 2, 3])
    ax.legend(['A simple line'])

Note: This call signature is discouraged, because the relation between
plot elements and labels is only implicit by their order and can
easily be mixed up.


**3. Explicitly defining the elements in the legend**

For full control of which artists have a legend entry, it is possible
to pass an iterable of legend artists followed by an iterable of
legend labels respectively::

    ax.legend([line1, line2, line3], ['label1', 'label2', 'label3'])

Parameters
----------
handles : sequence of `.Artist`, optional
    A list of Artists (lines, patches) to be added to the legend.
    Use this together with *labels*, if you need full control on what
    is shown in the legend and the automatic mechanism described above
    is not sufficient.

    The length of handles and labels should be the same in this
    case. If they are not, they are truncated to the smaller length.

labels : list of str, optional
    A list of labels to show next to the artists.
    Use this together with *handles*, if you need full control on what
    is shown in the legend and the automatic mechanism described above
    is not sufficient.

Returns
-------
`~matplotlib.legend.Legend`

Other Parameters
----------------

loc : str or pair of floats, default: :rc:`legend.loc` ('best' for axes, 'upper right' for figures)
    The location of the legend.

    The strings
    ``'upper left', 'upper right', 'lower left', 'lower right'``
    place the legend at the corresponding corner of the axes/figure.

    The strings
    ``'upper center', 'lower center', 'center left', 'center right'``
    place the legend at the center of the corresponding edge of the
    axes/figure.

    The string ``'center'`` places the legend at the center of the axes/figure.

    The string ``'best'`` places the legend at the location, among the nine
    locations defined so far, with the minimum overlap with other drawn
    artists.  This option can be quite slow for plots with large amounts of
    data; your plotting speed may benefit from providing a specific location.

    The location can also be a 2-tuple giving the coordinates of the lower-left
    corner of the legend in axes coordinates (in which case *bbox_to_anchor*
    will be ignored).

    For back-compatibility, ``'center right'`` (but no other location) can also
    be spelled ``'right'``, and each "string" locations can also be given as a
    numeric value:

        ===============   =============
        Location String   Location Code
        ===============   =============
        'best'            0
        'upper right'     1
        'upper left'      2
        'lower left'      3
        'lower right'     4
        'right'           5
        'center left'     6
        'center right'    7
        'lower center'    8
        'upper center'    9
        'center'          10
        ===============   =============

bbox_to_anchor : `.BboxBase`, 2-tuple, or 4-tuple of floats
    Box that is used to position the legend in conjunction with *loc*.
    Defaults to `axes.bbox` (if called as a method to `.Axes.legend`) or
    `figure.bbox` (if `.Figure.legend`).  This argument allows arbitrary
    placement of the legend.

    Bbox coordinates are interpreted in the coordinate system given by
    *bbox_transform*, with the default transform
    Axes or Figure coordinates, depending on which ``legend`` is called.

    If a 4-tuple or `.BboxBase` is given, then it specifies the bbox
    ``(x, y, width, height)`` that the legend is placed in.
    To put the legend in the best location in the bottom right
    quadrant of the axes (or figure)::

        loc='best', bbox_to_anchor=(0.5, 0., 0.5, 0.5)

    A 2-tuple ``(x, y)`` places the corner of the legend specified by *loc* at
    x, y.  For example, to put the legend's upper right-hand corner in the
    center of the axes (or figure) the following keywords can be used::

        loc='upper right', bbox_to_anchor=(0.5, 0.5)

ncol : int, default: 1
    The number of columns that the legend has.

prop : None or `matplotlib.font_manager.FontProperties` or dict
    The font properties of the legend. If None (default), the current
    :data:`matplotlib.rcParams` will be used.

fontsize : int or {'xx-small', 'x-small', 'small', 'medium', 'large', 'x-large', 'xx-large'}
    The font size of the legend. If the value is numeric the size will be the
    absolute font size in points. String values are relative to the current
    default font size. This argument is only used if *prop* is not specified.

labelcolor : str or list
    The color of the text in the legend. Either a valid color string
    (for example, 'red'), or a list of color strings. The labelcolor can
    also be made to match the color of the line or marker using 'linecolor',
    'markerfacecolor' (or 'mfc'), or 'markeredgecolor' (or 'mec').

numpoints : int, default: :rc:`legend.numpoints`
    The number of marker points in the legend when creating a legend
    entry for a `.Line2D` (line).

scatterpoints : int, default: :rc:`legend.scatterpoints`
    The number of marker points in the legend when creating
    a legend entry for a `.PathCollection` (scatter plot).

scatteryoffsets : iterable of floats, default: ``[0.375, 0.5, 0.3125]``
    The vertical offset (relative to the font size) for the markers
    created for a scatter plot legend entry. 0.0 is at the base the
    legend text, and 1.0 is at the top. To draw all markers at the
    same height, set to ``[0.5]``.

markerscale : float, default: :rc:`legend.markerscale`
    The relative size of legend markers compared with the originally
    drawn ones.

markerfirst : bool, default: True
    If *True*, legend marker is placed to the left of the legend label.
    If *False*, legend marker is placed to the right of the legend label.

frameon : bool, default: :rc:`legend.frameon`
    Whether the legend should be drawn on a patch (frame).

fancybox : bool, default: :rc:`legend.fancybox`
    Whether round edges should be enabled around the `~.FancyBboxPatch` which
    makes up the legend's background.

shadow : bool, default: :rc:`legend.shadow`
    Whether to draw a shadow behind the legend.

framealpha : float, default: :rc:`legend.framealpha`
    The alpha transparency of the legend's background.
    If *shadow* is activated and *framealpha* is ``None``, the default value is
    ignored.

facecolor : "inherit" or color, default: :rc:`legend.facecolor`
    The legend's background color.
    If ``"inherit"``, use :rc:`axes.facecolor`.

edgecolor : "inherit" or color, default: :rc:`legend.edgecolor`
    The legend's background patch edge color.
    If ``"inherit"``, use take :rc:`axes.edgecolor`.

mode : {"expand", None}
    If *mode* is set to ``"expand"`` the legend will be horizontally
    expanded to fill the axes area (or *bbox_to_anchor* if defines
    the legend's size).

bbox_transform : None or `matplotlib.transforms.Transform`
    The transform for the bounding box (*bbox_to_anchor*). For a value
    of ``None`` (default) the Axes'
    :data:`~matplotlib.axes.Axes.transAxes` transform will be used.

title : str or None
    The legend's title. Default is no title (``None``).

title_fontsize : int or {'xx-small', 'x-small', 'small', 'medium', 'large', 'x-large', 'xx-large'}, default: :rc:`legend.title_fontsize`
    The font size of the legend's title.

borderpad : float, default: :rc:`legend.borderpad`
    The fractional whitespace inside the legend border, in font-size units.

labelspacing : float, default: :rc:`legend.labelspacing`
    The vertical space between the legend entries, in font-size units.

handlelength : float, default: :rc:`legend.handlelength`
    The length of the legend handles, in font-size units.

handletextpad : float, default: :rc:`legend.handletextpad`
    The pad between the legend handle and text, in font-size units.

borderaxespad : float, default: :rc:`legend.borderaxespad`
    The pad between the axes and legend border, in font-size units.

columnspacing : float, default: :rc:`legend.columnspacing`
    The spacing between columns, in font-size units.

handler_map : dict or None
    The custom dictionary mapping instances or types to a legend
    handler. This *handler_map* updates the default handler map
    found at `matplotlib.legend.Legend.get_legend_handler_map`.


See Also
--------
.Figure.legend

Notes
-----
Some artists are not supported by this function.  See
:doc:`/tutorials/intermediate/legend_guide` for details.

Examples
--------
.. plot:: gallery/text_labels_and_annotations/legend.py