Function _add_legend

xarray/plot/utils.py:1714–1752

(
    hueplt_norm: _Normalize,
    sizeplt_norm: _Normalize,
    primitive,
    legend_ax,
    plotfunc: str,
)

def _add_legend(
    hueplt_norm: _Normalize,
    sizeplt_norm: _Normalize,
    primitive,
    legend_ax,
    plotfunc: str,
):
    primitive = primitive if isinstance(primitive, list) else [primitive]

    handles, labels = [], []
    for huesizeplt, prop in [
        (hueplt_norm, "colors"),
        (sizeplt_norm, "sizes"),
    ]:
        if huesizeplt.data is not None:
            # Get legend handles and labels that displays the
            # values correctly. Order might be different because
            # legend_elements uses np.unique instead of pd.unique,
            # FacetGrid.add_legend might have troubles with this:
            hdl, lbl = [], []
            for p in primitive:
                hdl_, lbl_ = legend_elements(p, prop, num="auto", func=huesizeplt.func)
                hdl += hdl_
                lbl += lbl_

            # Only save unique values:
            u, ind = np.unique(lbl, return_index=True)
            ind = np.argsort(ind)
            lbl = cast(list, u[ind].tolist())
            hdl = cast(list, np.array(hdl)[ind].tolist())

            # Add a subtitle:
            hdl, lbl = _legend_add_subtitle(hdl, lbl, label_from_attrs(huesizeplt.data))
            handles += hdl
            labels += lbl
    legend = legend_ax.legend(handles, labels, framealpha=0.5)
    _adjust_legend_subtitles(legend)

    return legend


def _guess_coords_to_plot(