sortcl

sort multiple angular power spectra in healpy input order

This is a minimal Python package to sort input angular power spectra cls into the order expected by healpy's synalm and synfast functions.

The package can be installed using pip:

pip install sortcl

Then import the sortcl function from the package:

from sortcl import sortcl

Current functionality covers the absolutely minimal use case. Please open an issue on GitHub if you would like to see anything added.

Documentation

def sortcl(cls, pairs, new=True):
    '''sort cls in healpy synalm/synfast order

    Given a list of cls and a list of pairs, return a new list of cls in the
    order that healpy's ``synalm`` and ``synfast`` expect.

    The list of pairs is any list of objects of length 2, for example strings:
    ``['TT', 'TE', 'TB']``.

    Parameters
    ----------
    cls : list
        List of objects that will be sorted.
    pairs : list of pairs
        An iterable of objects of length two.
    new : bool
        Sort along diagonals if ``True``, or along rows if ``False``.

    Returns
    -------
    sorted_cls : list
        Sorted list of objects. Missing entries are set to ``None``.

    Examples
    --------
    The typical use case is to bring a list of input cls into the right order
    to pass it to ``synalm``.

    >>> # 5 random example cls up to lmax = 1000
    >>> cls = np.random.rand(5, 1001)
    >>> pairs = ['TT', 'TE', 'TB', 'EE', 'BB']

    >>> from sortcl import sortcl
    >>> sorted_cls = sortcl(cls, pairs)

    To illustrate what's going on, we can use the fact that the cls can be any
    object, such as the labels themselves.

    >>> sortcl(pairs, pairs)
    ['TT', 'EE', 'BB', 'TE', None, 'TB']

    >>> # can also sort in old order, along rows
    >>> sortcl(pairs, pairs, new=False)
    ['TT', 'TE', 'TB', 'EE', None, 'BB']

    '''