def sort_by_attr(seq, attr):
"""Sort the sequence of objects by object's attribute
Arguments:
seq - the list or any sequence (including immutable one) of objects to sort.
attr - the name of attribute to sort by
Returns:
the sorted list of objects.
"""
import operator
# Use the "Schwartzian transform"
# Create the auxiliary list of tuples where every i-th tuple has form
# (seq[i].attr, i, seq[i]) and sort it. The second item of tuple is needed not
# only to provide stable sorting, but mainly to eliminate comparison of objects
# (which can be expensive or prohibited) in case of equal attribute values.
intermed = map(None, map(getattr, seq, (attr,)*len(seq)), xrange(len(seq)), seq)
intermed.sort()
return map(operator.getitem, intermed, (-1,) * len(intermed))
def sort_by_attr_inplace(lst, attr):
"""Inplace sort the list of objects by object's attribute
"""
lst[:] = sort_by_attr(lst, attr)
