def test_drop_obs_column():
    adata = ad.AnnData(np.array(X_list), obs=obs_dict, dtype="int32")

    subset = adata[:2]
    assert subset.is_view
    # returns a copy of obs
    assert subset.obs.drop(columns=["oanno1"]).columns.tolist() == ["oanno2", "oanno3"]
    assert subset.is_view
    # would modify obs, so it should actualize subset and not modify adata
    subset.obs.drop(columns=["oanno1"], inplace=True)
    assert not subset.is_view
    assert subset.obs.columns.tolist() == ["oanno2", "oanno3"]

    assert adata.obs.columns.tolist() == ["oanno1", "oanno2", "oanno3"]
def __init__(self, head):
        self.head = head
        self.lsize = 0
        while head.next:
            head = head.next
            self.lsize += 1

        self.m1_idx = None
        self.m2_idx = None
        if self.lsize > self._largesize:
            self.m1_idx = self.lsize / 3   # start from 1/3
            self.m1 = self._getN(self.m1_idx)
            self.m2_idx = self.m1_idx * 2  # start from 2/3
            self.m2 = self._getN(self.m2_idx)