tractor.py

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#
# LSST Data Management System
# Copyright 2008-2013 LSST Corporation.
#
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
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# GNU General Public License for more details.
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"""Code to load multi-Gaussian approximations to profiles from "The Tractor"
into a lsst.shapelet.MultiShapeletBasis.
 
Please see the README file in the data directory of the lsst.shapelet
package for more information.
"""
import numpy
import os
import re
import sys
import warnings
import pickle
 
import lsst.pex.exceptions
from .radialProfile import RadialProfile
from .multiShapeletBasis import MultiShapeletBasis
from .shapeletFunction import ShapeletFunction
 
 
def registerRadialProfiles():
    """Register the pickled profiles in the data directory with the RadialProfile
    singleton registry.
 
    This should only be called at import time by this module; it's only a function to
    avoid polluting the module namespace with all the local variables used here.
    """
    dataDir = os.path.join(os.environ["SHAPELET_DIR"], "data")
    regex = re.compile(r"([a-z]+\d?)_K(\d+)_MR(\d+)\.pickle")
    for filename in os.listdir(dataDir):
        match = regex.match(filename)
        if not match:
            continue
        name = match.group(1)
        nComponents = int(match.group(2))
        maxRadius = int(match.group(3))
        try:
            profile = RadialProfile.get(name)
        except lsst.pex.exceptions.Exception:
            warnings.warn("No C++ profile for multi-Gaussian pickle file '%s'" % filename)
            continue
        with open(os.path.join(dataDir, filename), 'rb') as stream:
            if sys.version_info[0] >= 3:
                array = pickle.load(stream, encoding='latin1')
            else:
                array = pickle.load(stream)
        amplitudes = array[:nComponents]
        amplitudes /= amplitudes.sum()
        variances = array[nComponents:]
        if amplitudes.shape != (nComponents,) or variances.shape != (nComponents,):
            warnings.warn("Unknown format for multi-Gaussian pickle file '%s'" % filename)
            continue
        basis = MultiShapeletBasis(1)
        for amplitude, variance in zip(amplitudes, variances):
            radius = variance**0.5
            matrix = numpy.array([[amplitude / ShapeletFunction.FLUX_FACTOR]], dtype=float)
            basis.addComponent(radius, 0, matrix)
        profile.registerBasis(basis, nComponents, maxRadius)
 
 
# We register all the profiles at module import time, to allow C++ code to access all available profiles
# without having to later call Python code to unpickle them.
registerRadialProfiles()
 
 
def evaluateRadial(basis, r, sbNormalize=False, doComponents=False):
    """Plot a single-element MultiShapeletBasis as a radial profile.
 
    Parameters
    ----------
    sbNormalize : `bool`
        `True` to normalize.
    doComponents : `bool`
        `True` to evaluate components.
    """
    ellipse = lsst.afw.geom.ellipses.Ellipse(lsst.afw.geom.ellipses.Axes())
    coefficients = numpy.ones(1, dtype=float)
    msf = basis.makeFunction(ellipse, coefficients)
    ev = msf.evaluate()
    n = 1
    if doComponents:
        n += len(msf.getComponents())
    z = numpy.zeros((n,) + r.shape, dtype=float)
    for j, x in enumerate(r):
        z[0, j] = ev(x, 0.0)
    if doComponents:
        for i, sf in enumerate(msf.getComponents()):
            evc = sf.evaluate()
            for j, x in enumerate(r):
                z[i+1, j] = evc(x, 0.0)
    if sbNormalize:
        z /= ev(1.0, 0.0)
    return z
 
 
def integrateNormalizedFluxes(maxRadius=20.0, nSteps=5000):
    """Integrate the profiles to compare relative fluxes between the true profiles
    and their approximations.
 
    After normalizing by surface brightness at r=1 r_e, integrate the profiles to compare
    relative fluxes between the true profiles and their approximations.
 
    Parameters
    ----------
    maxRadius : `float`, optional
        Maximum radius to integrate the profile, in units of r_e.
    nSteps : `int`, optional
        Number of concrete points at which to evaluate the profile to
        do the integration (we just use the trapezoidal rule).
 
    Returns
    -------
    fluxes : `dict` of `float` values
        Dictionary of fluxes (``exp``, ``lux``, ``dev``, ``luv``, ``ser2``, ``ser3``,
        ``ser5``, ``gexp``,  ``glux``, ``gdev``, ``gluv``, ``gser2``, ``gser3``, ``gser5``)
    """
    radii = numpy.linspace(0.0, maxRadius, nSteps)
    profiles = {name: RadialProfile.get(name) for name in ("exp", "lux", "dev", "luv",
                                                           "ser2", "ser3", "ser5")}
    evaluated = {}
    for name, profile in profiles.items():
        evaluated[name] = profile.evaluate(radii)
        basis = profile.getBasis(8)
        evaluated["g" + name] = evaluateRadial(basis, radii, sbNormalize=True, doComponents=False)[0, :]
    fluxes = {name: numpy.trapz(z*radii, radii) for name, z in evaluated.items()}
    return fluxes
 
 
def plotSuite(doComponents=False):
    """Plot all the profiles defined in this module together.
 
    Plot all the profiles defined in this module together: true exp and dev,
    the SDSS softened/truncated lux and luv, and the multi-Gaussian approximations
    to all of these.
 
    Parameters
    ----------
    doComponents : `bool`, optional
        True, to plot the individual Gaussians that form the multi-Gaussian approximations.
 
    Returns
    -------
    figure : `matplotlib.figure.Figure`
        Figure that contains the plot.
    axes : `numpy.ndarray` of `matplotlib.axes.Axes`
        A 2x4 NumPy array of matplotlib axes objects.
    """
    from matplotlib import pyplot
    fig = pyplot.figure(figsize=(9, 4.7))
    axes = numpy.zeros((2, 4), dtype=object)
    r1 = numpy.logspace(-3, 0, 1000, base=10)
    r2 = numpy.linspace(1, 10, 1000)
    r = [r1, r2]
    for i in range(2):
        for j in range(4):
            axes[i, j] = fig.add_subplot(2, 4, i*4+j+1)
    profiles = {name: RadialProfile.get(name) for name in ("exp", "lux", "dev", "luv")}
    basis = {name: profiles[name].getBasis(8) for name in profiles}
    z = numpy.zeros((2, 4), dtype=object)
    colors = ("k", "g", "b", "r")
    fig.subplots_adjust(wspace=0.025, hspace=0.025, bottom=0.15, left=0.1, right=0.98, top=0.92)
    centers = [None, None]
    for i in range(2):   # 0=profile, 1=relative error
        for j in range(0, 4, 2):  # grid columns: 0=exp-like, 2=dev-like
            bbox0 = axes[i, j].get_position()
            bbox1 = axes[i, j+1].get_position()
            bbox1.x0 = bbox0.x1 - 0.06
            bbox0.x1 = bbox1.x0
            centers[j//2] = 0.5*(bbox0.x0 + bbox1.x1)
            axes[i, j].set_position(bbox0)
            axes[i, j+1].set_position(bbox1)
    for j in range(0, 2):
        z[0, j] = [evaluateRadial(basis[k], r[j], sbNormalize=True, doComponents=doComponents)
                   for k in ("exp", "lux")]
        z[0, j][0:0] = [profiles[k].evaluate(r[j])[numpy.newaxis, :] for k in ("exp", "lux")]
        z[0, j+2] = [evaluateRadial(basis[k], r[j], sbNormalize=True, doComponents=doComponents)
                     for k in ("dev", "luv")]
        z[0, j+2][0:0] = [profiles[k].evaluate(r[j])[numpy.newaxis, :] for k in ("dev", "luv")]
    methodNames = [["loglog", "semilogy"], ["semilogx", "plot"]]
    for j in range(0, 4):  # grid columns
        z[1, j] = [(z[0, j][0][0, :] - z[0, j][i][0, :])/z[0, j][0][0, :] for i in range(0, 4)]
        handles = []
        method0 = getattr(axes[0, j], methodNames[0][j%2])
        method1 = getattr(axes[1, j], methodNames[1][j%2])
        for k in range(4):
            y0 = z[0, j][k]
            handles.append(method0(r[j%2], y0[0, :], color=colors[k])[0])
            if doComponents:
                for l in range(1, y0.shape[0]):
                    method0(r[j%2], y0[l, :], color=colors[k], alpha=0.25)
            method1(r[j%2], z[1, j][k], color=colors[k])
        axes[0, j].set_xticklabels([])
        axes[0, j].set_ylim(1E-6, 1E3)
        axes[1, j].set_ylim(-0.2, 1.0)
    for i, label in enumerate(("profile", "relative error")):
        axes[i, 0].set_ylabel(label)
        for t in axes[i, 0].get_yticklabels():
            t.set_fontsize(11)
    for j in range(1, 4):
        axes[0, j].set_yticklabels([])
        axes[1, j].set_yticklabels([])
    xticks = [['$\\mathdefault{10^{%d}}$' % i for i in range(-3, 1)],
              [str(i) for i in range(1, 11)]]
    xticks[0][-1] = ""
    xticks[1][-1] = ""
    for j in range(0, 4):
        axes[1, j].set_xticklabels(xticks[j%2])
        for t in axes[1, j].get_xticklabels():
            t.set_fontsize(11)
    fig.legend(handles, ["exp/dev", "lux/luv", "approx exp/dev", "approx lux/luv"],
               loc='lower center', ncol=4)
    fig.text(centers[0], 0.95, "exponential", ha='center', weight='bold')
    fig.text(centers[1], 0.95, "de Vaucouleur", ha='center', weight='bold')
    return fig, axes