fix bug with metacal psf method "gauss"

CHANGES.md

@@ -1,3 +1,10 @@
+## v2.3.1
+
+## Bug Fixes
+
+    - The metacal psf reconvolution method 'gauss' (which uses MetacalGaussPSF)
+      now works with a complex WCS
+
 ## v2.3.0
 
 ### new features

mdet_tests/test_mdet_regression.py

@@ -268,7 +268,7 @@ def test_mdet_regression(fname, write=False):
                     ),
                 }
             else:
-                assert col in ["shear", "shear_bands"]
+                assert col in ["det_bands", "shear", "shear_bands"]
 
 
 if __name__ == "__main__":

ngmix/_version.py

@@ -1 +1 @@
-__version__ = '2.3.0'  # noqa
+__version__ = '2.3.1'  # noqa

ngmix/metacal/metacal.py

@@ -419,6 +419,7 @@ def _set_data(self):
         # interpolated psf deconvolved from pixel.  This is what
         # we dilate, shear, etc and reconvolve the image by
         self.psf_int_nopix = galsim.Convolve([psf_int, self.pixel_inv])
+        self.psf_int = psf_int
 
     def get_wcs(self):
         """
@@ -572,15 +573,15 @@ def _get_dilated_psf(self, shear, doshear=False):
         _do_dilate for the algorithm
 
         """
-        import galsim
+        # import galsim
 
         assert doshear is False, 'no shearing gauss psf'
 
         gauss_psf = _get_gauss_target_psf(
-            self.psf_int_nopix, flux=self.psf_flux,
+            self.psf_int,
+            flux=self.psf_flux,
         )
-        psf_grown_nopix = _do_dilate(gauss_psf, shear)
-        psf_grown = galsim.Convolve(psf_grown_nopix, self.pixel)
+        psf_grown = _do_dilate(gauss_psf, shear)
         return psf_grown
 
     def _make_psf_obs(self, gsim):

ngmix/observation.py

@@ -463,8 +463,9 @@ def set_ormask(self, ormask):
             ormask = np.ascontiguousarray(ormask)
             assert len(ormask.shape) == 2, "ormask must be 2d"
 
-            assert (ormask.shape == image.shape),\
+            assert (ormask.shape == image.shape), (
                 "image and ormask must be same shape"
+            )
 
             self._ormask = ormask
 
@@ -1006,8 +1007,9 @@ def append(self, obs_list):
             An ObsList. An AssertionError will be raised if `obs_list` is not
             an `ngmix.ObsList`.
         """
-        assert isinstance(obs_list, ObsList),\
+        assert isinstance(obs_list, ObsList), (
             'obs_list should be of type ObsList'
+        )
         super(MultiBandObsList, self).append(obs_list)
 
     def get_s2n(self):
@@ -1092,8 +1094,9 @@ def __setitem__(self, index, obs_list):
         """
         over-riding this for type safety
         """
-        assert isinstance(obs_list, ObsList),\
+        assert isinstance(obs_list, ObsList), (
             'obs_list should be of type ObsList'
+        )
         super(MultiBandObsList, self).__setitem__(index, obs_list)
 
 
@@ -1306,8 +1309,9 @@ def __setitem__(self, index, kobs):
         """
         over-riding this for type safety
         """
-        assert isinstance(kobs, KObservation),\
+        assert isinstance(kobs, KObservation), (
             'kobs should be of type KObservation'
+        )
         super(KObsList, self).__setitem__(index, kobs)
 
 

ngmix/tests/test_metacal_accuracy.py

@@ -0,0 +1,218 @@
+import numpy as np
+import ngmix
+import galsim
+import pytest
+
+
+@pytest.mark.parametrize('psf', ['gauss', 'fitgauss', 'galsim_obj'])
+def test_metacal_accuracy(psf):
+
+    ntrial = 100
+    seed = 99
+
+    if psf == 'galsim_obj':
+        psf = galsim.Gaussian(fwhm=1.05)
+
+    # Wacky WCS
+    wcs_g1 = 0.1
+    wcs_g2 = 0.0
+    wcs = galsim.ShearWCS(0.263, galsim.Shear(g1=wcs_g1, g2=wcs_g2)).jacobian()
+
+    print("WCS:", wcs.getDecomposition())
+    print()
+    print()
+
+    shear_true = 0.02
+    rng = np.random.RandomState(seed)
+
+    # We will measure moments with a fixed gaussian weight function
+    weight_fwhm = 1.2
+    fitter = ngmix.gaussmom.GaussMom(fwhm=weight_fwhm)
+    psf_fitter = ngmix.gaussmom.GaussMom(fwhm=weight_fwhm)
+
+    # these "runners" run the measurement code on observations
+    psf_runner = ngmix.runners.PSFRunner(fitter=psf_fitter)
+    runner = ngmix.runners.Runner(fitter=fitter)
+
+    # this "bootstrapper" runs the metacal image shearing as well as both psf
+    # and object measurements
+    boot = ngmix.metacal.MetacalBootstrapper(
+        runner=runner, psf_runner=psf_runner,
+        rng=rng,
+        psf=psf,
+        types=['noshear', '1p', '1m'],
+    )
+    dlist = []
+    for i in range(ntrial):
+        im, psf_im, obs = _make_data(rng=rng, shear=shear_true, wcs=wcs)
+        resdict, obsdict = boot.go(obs)
+        for stype, sres in resdict.items():
+            st = _make_struct(res=sres, obs=obsdict[stype], shear_type=stype)
+            dlist.append(st)
+
+    print()
+    data = np.hstack(dlist)
+
+    w = _select(data=data, shear_type='noshear')
+    w_1p = _select(data=data, shear_type='1p')
+    w_1m = _select(data=data, shear_type='1m')
+
+    g1 = data['g'][w, 0].mean()
+    g1err = data['g'][w, 0].std() / np.sqrt(w.size)
+    g1_1p = data['g'][w_1p, 0].mean()
+    g1_1m = data['g'][w_1m, 0].mean()
+
+    R11 = (g1_1p - g1_1m)/0.02
+
+    shear = g1 / R11
+    shear_err = g1err / R11
+    m = shear / shear_true - 1
+    merr = shear_err / shear_true
+
+    s2n = data['s2n'][w].mean()
+    print('S/N: %g' % s2n)
+    print('R11: %g' % R11)
+    print('m: %g +/- %g (99.7%% conf)' % (m, merr*3))
+
+    assert np.abs(m - 0.00034) < 1.0e-4
+
+
+def _make_struct(res, obs, shear_type):
+    """
+    make the data structure
+    Parameters
+    ----------
+    res: dict
+        With keys 's2n', 'e', and 'T'
+    obs: ngmix.Observation
+        The observation for this shear type
+    shear_type: str
+        The shear type
+    Returns
+    -------
+    1-element array with fields
+    """
+    dt = [
+        ('flags', 'i4'),
+        ('shear_type', 'U7'),
+        ('s2n', 'f8'),
+        ('g', 'f8', 2),
+        ('T', 'f8'),
+        ('Tpsf', 'f8'),
+    ]
+    data = np.zeros(1, dtype=dt)
+    data['shear_type'] = shear_type
+    data['flags'] = res['flags']
+    if res['flags'] == 0:
+        data['s2n'] = res['s2n']
+        # for moments we are actually measureing e, the elliptity
+        data['g'] = res['e']
+        data['T'] = res['T']
+    else:
+        data['s2n'] = np.nan
+        data['g'] = np.nan
+        data['T'] = np.nan
+        data['Tpsf'] = np.nan
+    # we only have one epoch and band, so we can get the psf T from the
+    # observation rather than averaging over epochs/bands
+    data['Tpsf'] = obs.psf.meta['result']['T']
+    return data
+
+
+def _select(data, shear_type):
+    """
+    select the data by shear type and size
+    Parameters
+    ----------
+    data: array
+        The array with fields shear_type and T
+    shear_type: str
+        e.g. 'noshear', '1p', etc.
+    Returns
+    -------
+    array of indices
+    """
+    # raw moments, so the T is the post-psf T.  This the
+    # selection is > 1.2 rather than something smaller like 0.5
+    # for pre-psf T from one of the maximum likelihood fitters
+    wtype, = np.where(
+        (data['shear_type'] == shear_type) &
+        (data['flags'] == 0)
+    )
+    w, = np.where(data['T'][wtype]/data['Tpsf'][wtype] > 1.2)
+    print('%s kept: %d/%d' % (shear_type, w.size, wtype.size))
+    w = wtype[w]
+    return w
+
+
+def _make_data(rng, shear, wcs):
+    """
+    simulate an exponential object with moffat psf
+    the hlr of the exponential is drawn from a gaussian
+    with mean 0.4 arcseconds and sigma 0.2
+    Parameters
+    ----------
+    rng: np.random.RandomState
+        The random number generator
+    noise: float
+        Noise for the image
+    shear: (g1, g2)
+        The shear in each component
+    Returns
+    -------
+    ngmix.Observation
+    """
+    noise = 1.0e-8
+    psf_noise = 1.0e-8
+    stamp_size = 91
+
+    psf_fwhm = 0.9
+    gal_hlr = 0.5
+    psf = galsim.Moffat(
+        beta=2.5,
+        fwhm=psf_fwhm,
+    ).shear(
+        g1=0.02,
+        g2=-0.01,
+    )
+    obj0 = galsim.Exponential(
+        half_light_radius=gal_hlr,
+    ).shear(
+        g1=shear,
+    )
+    obj = galsim.Convolve(psf, obj0)
+
+    psf_im = psf.drawImage(nx=stamp_size, ny=stamp_size, wcs=wcs).array
+    im = obj.drawImage(nx=stamp_size, ny=stamp_size, wcs=wcs).array
+
+    psf_im += rng.normal(scale=psf_noise, size=psf_im.shape)
+    im += rng.normal(scale=noise, size=im.shape)
+
+    cen = (np.array(im.shape)-1.0)/2.0
+    psf_cen = (np.array(psf_im.shape)-1.0)/2.0
+
+    jacobian = ngmix.Jacobian(
+        x=cen[1], y=cen[0], wcs=wcs.jacobian(
+            image_pos=galsim.PositionD(cen[1], cen[0])
+        ),
+    )
+    psf_jacobian = ngmix.Jacobian(
+        x=psf_cen[1], y=psf_cen[0], wcs=wcs.jacobian(
+            image_pos=galsim.PositionD(psf_cen[1], psf_cen[0])
+        ),
+    )
+
+    wt = im*0 + 1.0/noise**2
+    psf_wt = psf_im*0 + 1.0/psf_noise**2
+    psf_obs = ngmix.Observation(
+        psf_im,
+        weight=psf_wt,
+        jacobian=psf_jacobian,
+    )
+    obs = ngmix.Observation(
+        im,
+        weight=wt,
+        jacobian=jacobian,
+        psf=psf_obs,
+    )
+    return im, psf_im, obs

ngmix/tests/test_metacal_bootstrap.py

@@ -178,6 +178,4 @@ def test_metacal_bootstrap_gaussmom_response(metacal_caching):
         Rvals[i] = (res1p['e'][0] - res1m['e'][0])/0.02
 
     Rmean = Rvals.mean()
-    # this response value comes from 2.0.0, and had an error less than of
-    # 1.0e-5 on it.  Allow for differences in rng/arch etc. by taking 1.0e-4
-    assert abs(Rmean - 0.28535) < 1.0e-4
+    assert abs(Rmean - 0.28159) < 1.0e-4