python – 嵌套数据的复杂排序

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# -*- coding: utf-8 -*-

from __future__ import print_function
from functools import cmp_to_key
import collections
import urllib2
import json

def sort_it(obj=None,sort_order=None):
    """Sort a composite python object.

    :param obj: Python object
    :param sort_order: optional custom sort order
    :rtype: OrderedDict
    :returns: Sorted composite object.
    """

    # TODO: Refactor to use key rather than cmp (cmp is not supported in python3)
    # using cmp_to_key as transitional solution
    text_types = (basestring,int,float,complex)
    iterable_types = (list,tuple,set,frozenset)

    def cmp_func(a,b):
        """Function passed as `cmp` arg to sorted method

        Basic Algorithm
        - text_types take precedence over non text_types
        - Mapping types take precedence over iterable container types
        - Values of the same (or similar) type:
           - if sort_order is defined
              - if both keys are in sort order,the key index position determines precedence
              - if only one of the keys are in sort order then it takes precedence
              - if neither keys are in sort_order their lexicographic order is the determinant
           - otherwise,fall back to lexicographic ordering

        :param a: first arg passed to sorted's cmp arg
        :param b: second arg passed to sorted's cmp arg
        :rtype: int
        :return: int to determine which object (a/b) should take precedence
        """

        # ensure a and b are k/v pairs
        if not any([len(a) == 2,len(b) == 2]):
            return 0

        # text_types take precedence over non-text types
        elif isinstance(a[1],text_types) and not isinstance(b[1],text_types):
            return -1
        elif not isinstance(a[1],text_types) and isinstance(b[1],text_types):
            return 1

        # Mappings take precedence over iterable types
        elif isinstance(a[1],collections.Mapping) and isinstance(b[1],iterable_types):
            return -1
        elif isinstance(b[1],collections.Mapping) and isinstance(a[1],iterable_types):
            return 1

        # if type of values are of the same/similar type
        elif any([isinstance(a[1],text_types),isinstance(a[1],iterable_types) and isinstance(b[1],iterable_types),collections.Mapping),type(b[1])),]):
            if sort_order:
                if any([a[0] in sort_order,b[0] in sort_order]):
                    if a[0] in sort_order and b[0] not in sort_order:
                        return -1
                    if b[0] in sort_order and a[0] not in sort_order:
                        return 1
                    if a[0] in sort_order and b[0] in sort_order:
                        if sort_order.index(a[0]) > sort_order.index(b[0]):
                            return 1
                        else:
                            return -1
            # no sort_order ( or keys not in sort_order) -- sort lexicographically
            if sorted([a[0].lower(),b[0].lower()]).index(a[0].lower()) == 0:
                return -1
            elif sorted([a[0].lower(),b[0].lower()]).index(a[0].lower()) == 1:
                return 1
        else:
            raise ValueError('Unhandled condition for values %s,%s' % (a,b))

    if isinstance(obj,collections.Mapping):
        return collections.OrderedDict(
            (key,sort_it(value,sort_order=sort_order)) for key,value in
            sorted(obj.items(),key=cmp_to_key(cmp_func)))
    elif isinstance(obj,iterable_types):
        return type(obj)([sort_it(value,sort_order=sort_order) for value in obj])
    else:
        return obj

sort_order = [
    'id','rn','dn','vendor','model','serial','name','description','tray'
    'presence'
]

sample_data_uri = 'https://bit.ly/1jOpQF2'


### EXAMPLE - Sans sort order

print(json.dumps(sort_it(json.loads(urllib2.urlopen(sample_data_uri).read())),indent=4))

### EXAMPLE - with sort_order

print(json.dumps(sort_it(json.loads(urllib2.urlopen(sample_data_uri).read()),sort_order=sort_order),indent=4))