Merge data structures in python

merge_ds.py

import json
import itertools
from mergedict import ConfigDict

# minor changes to original code at http://stackoverflow.com/questions/19378143/python-merging-two-arbitrary-data-structures
def merge(a, b):
  if isinstance(a, dict) and isinstance(b, dict):
    d = dict(a)
    d.update({k: merge(a.get(k, None), b[k]) for k in b})
    return d

  if isinstance(a, list) and isinstance(b, list):
    is_a_nested = any(x for x in a if isinstance(x, list) or isinstance(x, dict))
    is_b_nested = any(x for x in b if isinstance(x, list) or isinstance(x, dict))
    if is_a_nested or is_b_nested:
      return [merge(x, y) for x, y in itertools.izip_longest(a, b)]
    else:
      return a + b

  return a if b is None else b


ds1 = {
  "name": "saurabh",
  "values": ["a", "b", "c"],
  "in_ds1": "here",
  "clean_nesting": {
    "l1": {
      "l2": {
        "l3": {
          "l4": {
            "what": [{"age": "2"}]
          }
        }
      }
    }
  },
  "arbitary_nesting": {
    "k1": {
      "k2": {
        "k3": [1,2,3]
      }
    }
  }
}
ds2 = {
  "name": "whoknows",
  "values": ["d", "e", "f"],
  "in_ds2": "there",
  "clean_nesting": {
    "l1": {
      "l2": {
        "l3": {
          "l4": {
            "what": [{"name": "1"}, "12"]
          }
        }
      }
    }
  },
  "arbitary_nesting": {
    "k1": {
      "k2": {
        "k4": {"k5": "k6"}
      }
    }
  }
}
ds3 = {
  'a': 1,
  'b': [1,2,3],
  'c': {
    'd': [
      [3, 4],
      4,
      {
        'a': {
          'b': [11,12,13]
        }
      }
    ]
  }
}

ds4 = {
  'a': 2,
  'b': [4,5,6],
  'c': {
    'd': [
      [1,2,3],
      2,
      {
        'a': {
          'b': [14,15]
        }
      },
    ]
  }
}

print "------------"
print json.dumps(ds1, indent=2)
print "------------"
print json.dumps(ds2, indent=2)
print "------------"
print json.dumps(merge(ds1, ds2), indent=2)
print "================"
print json.dumps(ds3, indent=2)
print "------------"
print json.dumps(ds4, indent=2)
print "------------"
print json.dumps(merge(ds3, ds4), indent=2)
print "================"
print json.dumps(merge([1,2,3], [4,5,6]), indent=2)
print "----------"