Improve union method for a list of MOC

[ggreco77]

It could be nice to improve the union method for a list of MOC - MOC.union(list).

[ggreco77]

I tried to add a new method to the class AbstractMoc named union_moc_list for fast union of a list of moc

def union_moc_list(self, another_mocs = [] ):
    """
    Union between self and a list of mocs

    Parameters
    ----------
    another_mocs : `~mocpy.abstract_moc.AbstractMoc`
        a list of MOC/TimeMoc to bind to self

    Returns
    -------
    result : `~mocpy.moc.MOC` or `~mocpy.tmoc.TimeMoc`
        MOC object whose interval set corresponds to : self | ``moc``

    """
    for another_moc in another_mocs:
        iv_set_union = self._interval_set.union(another_moc._interval_set)
        result = self.__class__.from_interval_set(iv_set_union)
        self = result

    return result

[bmatthieu3]

@ggreco77 What do you think of redefining the current AbstractMOC.union method like that:
def union(self, *args)

You can call the method like that:
moc1.union(moc2, moc3, ..., mocN)
Or if you have a list of MOCs :
moc1.union(*moc_l)

[bmatthieu3]

Or even like that def union(self, another_moc, *args) so that at least one moc is mandatory for computing an union of MOCs.

[tboch]

@ggreco77 What do you think of redefining the current AbstractMOC.union method like that:
def union(self, *args)

You can call the method like that:
moc1.union(moc2, moc3, ..., mocN)
Or if you have a list of MOCs :
moc1.union(*moc_l)

That would be my preferred API, def union(self, another_moc, *args) looks less natural to me.

[ggreco77]

Let me show you an real application of such new method
http://nbviewer.jupyter.org/gist/ggreco77/c114dd9f7364a216bd83602cee156ca3
as reported in "Ex. 1 Group the Observation in g filter - measure the sky area and the skymap intersection"
in the first lines

many thanks

[ggreco77]

I got some troubles with the union method implemented as union(self, another_moc, *args);

mocs= [moc1, moc2, moc3, moc4]

for moc in mocs: uni_mocs = MOC.union(moc)

How can obtain such statement using for or similar passing a list?

thanks!

[bmatthieu3]

Union/difference/intersection are not static (hmm just thinking it may be a good idea to do static functions taking multiple mocs through *args).

But for now if you have one moc object and a list of other mocs other_mocs_l=[moc2, ..., mocN] you can do the union of moc with the list by doing:
uni_mocs = moc.union(*other_mocs_l) or uni_mocs = moc.union(moc2, moc3, ..., mocN)
The * operator transforms a list say l=[1,2,3] in the following of values 1, 2, 3 that can be given in a function through the *args parameter name.
uni_mocs stores the result. moc is not changed after the method call. No needs to do a for loop.

[ggreco77]

Very clear, the method perfectly works in my scripts.
Many thanks.