fix: CMBLensed handling monopole and dipole

CHANGES.rst

@@ -7,6 +7,7 @@
 - Updated `pixell` from 0.17.3 to 0.26.0 https://github.com/galsci/pysm/pull/183
 - Initial implementation of a point source catalog component emission https://github.com/galsci/pysm/pull/187
 - Switch the build system to Hatch https://github.com/galsci/pysm/pull/189
+- Fix bug in `CMBLensed` to read spectra that include monopole and dipole
 
 3.4.0 (2023-12-11)
 ==================

src/pysm3/models/cmb.py

@@ -278,6 +278,14 @@ def __init__(
         self.delensing_ells = (
             None if delensing_ells is None else self.read_txt(delensing_ells)
         )
+
+        # Remove monopole and dipole, if present in cmb_spectra
+        if self.cmb_spectra[0][0] == 0:
+            self.cmb_spectra = self.cmb_spectra[:, 2:]
+        # Remove monopole and dipole, if present in delensing_ells
+        if self.apply_delens and self.delensing_ells[0][0] == 0:
+            self.delensing_ells = self.delensing_ells[:, 2:]
+
         self.map = u.Quantity(self.run_taylens(), unit=u.uK_CMB, copy=False)
 
     def run_taylens(self):

tests/test_cmb.py

@@ -1,6 +1,7 @@
 import numpy as np
 import pytest
 from astropy.tests.helper import assert_quantity_allclose
+from unittest.mock import patch
 
 import pysm3
 import pysm3.units as u
@@ -72,3 +73,66 @@ def test_cmb_lensed(model_tag, freq):
     assert_quantity_allclose(
         expected_output, model.get_emission(freq * u.GHz), rtol=1e-5
     )
+
+
+@pytest.mark.parametrize("freq", [100])
+def test_cmb_lensed_l01(freq):
+
+    model_number = 5
+    expected_output = pysm3.read_map(
+        f"pysm_2_test_data/check{model_number}cmb_{freq}p0_64.fits",
+        64,
+        unit="uK_RJ",
+        field=(0, 1, 2),
+    )
+
+    # Use a temporary model to get access to the read_txt method
+    temp_model = pysm3.Model(nside=64)
+    c1_spectra = temp_model.read_txt('pysm_2/camb_lenspotentialCls.dat',
+                                     unpack=True)
+    c1_delens_l = temp_model.read_txt('pysm_2/delens_ells.txt',
+                                      unpack=True)
+
+    # This portion should always pass
+    with patch.object(target=pysm3.models.cmb.CMBLensed, 
+                      attribute="read_txt", 
+                      side_effect=[c1_spectra, c1_delens_l]):
+        # The PySM test was done with a different seed than the one
+        # baked into the preset models
+        c1 = pysm3.models.cmb.CMBLensed(
+            nside=64,
+            cmb_spectra='pysm_2/camb_lenspotentialCls.dat',
+            cmb_seed=1234
+        )
+        model = pysm3.Sky(nside=64, component_objects=[c1])
+
+        try:
+            assert_quantity_allclose(
+                expected_output, 
+                model.get_emission(freq * u.GHz), 
+                rtol=1e-5
+            )
+        except AssertionError:
+            pytest.fail(f"Unexpected AssertionError. Superfail.")
+
+    # This portion should pass only with the fix
+
+    # Add rows of 0s for l=0,1
+    c1_spectra_l01 = np.zeros((c1_spectra.shape[0], c1_spectra.shape[1] + 2))
+    c1_spectra_l01[:, 2:] = c1_spectra
+
+    with patch.object(target=pysm3.models.cmb.CMBLensed,
+                      attribute="read_txt",
+                      side_effect=[c1_spectra_l01, c1_delens_l]):
+        c1 = pysm3.models.cmb.CMBLensed(
+            nside=64,
+            cmb_spectra='pysm_2/camb_lenspotentialCls.dat',
+            cmb_seed=1234
+        )
+        model = pysm3.Sky(nside=64, component_objects=[c1])
+
+        assert_quantity_allclose(
+            expected_output, 
+            model.get_emission(freq * u.GHz), 
+            rtol=1e-5
+        )