GPy/GPy/plotting/matplot_dep/kernel_plots.py

# Copyright (c) 2012, GPy authors (see AUTHORS.txt).
# Licensed under the BSD 3-clause license (see LICENSE.txt)

import numpy as np
import pylab as pb
import Tango
from matplotlib.textpath import TextPath
from matplotlib.transforms import offset_copy
from .base_plots import ax_default



def add_bar_labels(fig, ax, bars, bottom=0):
    transOffset = offset_copy(ax.transData, fig=fig,
                              x=0., y= -2., units='points')
    transOffsetUp = offset_copy(ax.transData, fig=fig,
                              x=0., y=1., units='points')
    for bar in bars:
        for i, [patch, num] in enumerate(zip(bar.patches, np.arange(len(bar.patches)))):
            if len(bottom) == len(bar): b = bottom[i]
            else: b = bottom
            height = patch.get_height() + b
            xi = patch.get_x() + patch.get_width() / 2.
            va = 'top'
            c = 'w'
            t = TextPath((0, 0), "${xi}$".format(xi=xi), rotation=0, ha='center')
            transform = transOffset
            if patch.get_extents().height <= t.get_extents().height + 3:
                va = 'bottom'
                c = 'k'
                transform = transOffsetUp
            ax.text(xi, height, "${xi}$".format(xi=int(num)), color=c, rotation=0, ha='center', va=va, transform=transform)
    
    ax.set_xticks([])


def plot_bars(fig, ax, x, ard_params, color, name, bottom=0):
    from ...util.misc import param_to_array
    return ax.bar(left=x, height=param_to_array(ard_params), width=.8, 
                  bottom=bottom, align='center', 
                  color=color, edgecolor='k', linewidth=1.2, 
                  label=name.replace("_"," "))

def plot_ARD(kernel, fignum=None, ax=None, title='', legend=False):
    """
    If an ARD kernel is present, plot a bar representation using matplotlib

    :param fignum: figure number of the plot
    :param ax: matplotlib axis to plot on
    :param title:
        title of the plot,
        pass '' to not print a title
        pass None for a generic title
    """
    fig, ax = ax_default(fignum,ax)

    if title is None:
        ax.set_title('ARD parameters, %s kernel' % kernel.name)
    else:
        ax.set_title(title)
    
    Tango.reset()
    bars = []
    
    ard_params = np.atleast_2d(kernel.input_sensitivity())
    bottom = 0
    x = np.arange(kernel.input_dim)
    
    for i in range(ard_params.shape[0]):
        c = Tango.nextMedium()
        bars.append(plot_bars(fig, ax, x, ard_params[i,:], c, kernel.parameters[i].name, bottom=bottom))
        bottom += ard_params[i,:]
    
    ax.set_xlim(-.5, kernel.input_dim - .5)
    add_bar_labels(fig, ax, [bars[-1]], bottom=bottom-ard_params[i,:])

    if legend:
        if title is '':
            mode = 'expand'
            if len(bars) > 1:
                mode = 'expand'
            ax.legend(bbox_to_anchor=(0., 1.02, 1., 1.02), loc=3,
                      ncol=len(bars), mode=mode, borderaxespad=0.)
            fig.tight_layout(rect=(0, 0, 1, .9))
        else:
            ax.legend()
    return ax


def plot(kernel, x=None, plot_limits=None, which_parts='all', resolution=None, *args, **kwargs):
    if which_parts == 'all':
        which_parts = [True] * kernel.size
    if kernel.input_dim == 1:
        if x is None:
            x = np.zeros((1, 1))
        else:
            x = np.asarray(x)
            assert x.size == 1, "The size of the fixed variable x is not 1"
            x = x.reshape((1, 1))

        if plot_limits == None:
            xmin, xmax = (x - 5).flatten(), (x + 5).flatten()
        elif len(plot_limits) == 2:
            xmin, xmax = plot_limits
        else:
            raise ValueError, "Bad limits for plotting"

        Xnew = np.linspace(xmin, xmax, resolution or 201)[:, None]
        Kx = kernel.K(Xnew, x)
        pb.plot(Xnew, Kx, *args, **kwargs)
        pb.xlim(xmin, xmax)
        pb.xlabel("x")
        pb.ylabel("k(x,%0.1f)" % x)

    elif kernel.input_dim == 2:
        if x is None:
            x = np.zeros((1, 2))
        else:
            x = np.asarray(x)
            assert x.size == 2, "The size of the fixed variable x is not 2"
            x = x.reshape((1, 2))

        if plot_limits == None:
            xmin, xmax = (x - 5).flatten(), (x + 5).flatten()
        elif len(plot_limits) == 2:
            xmin, xmax = plot_limits
        else:
            raise ValueError, "Bad limits for plotting"

        resolution = resolution or 51
        xx, yy = np.mgrid[xmin[0]:xmax[0]:1j * resolution, xmin[1]:xmax[1]:1j * resolution]
        xg = np.linspace(xmin[0], xmax[0], resolution)
        yg = np.linspace(xmin[1], xmax[1], resolution)
        Xnew = np.vstack((xx.flatten(), yy.flatten())).T
        Kx = kernel.K(Xnew, x, which_parts)
        Kx = Kx.reshape(resolution, resolution).T
        pb.contour(xg, yg, Kx, vmin=Kx.min(), vmax=Kx.max(), cmap=pb.cm.jet, *args, **kwargs) # @UndefinedVariable
        pb.xlim(xmin[0], xmax[0])
        pb.ylim(xmin[1], xmax[1])
        pb.xlabel("x1")
        pb.ylabel("x2")
        pb.title("k(x1,x2 ; %0.1f,%0.1f)" % (x[0, 0], x[0, 1]))
    else:
        raise NotImplementedError, "Cannot plot a kernel with more than two input dimensions"