Difference in a dict
I'm trying to figure out the difference in a dict, whether something was added or removed and from what.
Here is a case where a value is added:
original = {0: None, 1: False, 2: [16]}
new = {0: None, 1: False, 2: [2, 16]}
difference = True, {2: 2} # True = Added
And here is a case where a value is removed:
original = {0: None, 1: False, 2: [16, 64]}
new = {0: None, 1: False, 2: [64]}
difference = False, {2: 16} # False = Removed
The problem is that I have no idea how to recieve the difference. Would anyone happen to know how to achieve such a result?
Extra information (no idea if you'll need 开发者_运维百科this):
- This can apply to 0 and 1 of original and new as well.
- 1 and 2 cannot be active at the same time. If one has values, the other is False.
As I've explained in an other question there is a library on PyPI just for this task, which is datadiff library. It's easy to use and you can use the output to do what you have to do.
I find this quite readable:
def dict_diff(left, right):
diff = dict()
diff['left_only'] = set(left) - set(right)
diff['right_only'] = set(right) - set(left)
diff['different'] = {k for k in set(left) & set(right) if left[k]!=right[k]}
return diff
>>> d1 = dict(a=1, b=20, c=30, e=50)
>>> d2 = dict(a=1, b=200, d=400, e=500)
>>> dict_diff(d1, d2)
{'different': {'b', 'e'}, 'left_only': {'c'}, 'right_only': {'d'}}
Here is a link to a function that can produce a "diff" of two dictionaries, followed by additional comments/code samples:
http://code.activestate.com/recipes/576644-diff-two-dictionaries/
Including code below:
KEYNOTFOUND = '<KEYNOTFOUND>' # KeyNotFound for dictDiff
def dict_diff(first, second):
""" Return a dict of keys that differ with another config object. If a value is
not found in one fo the configs, it will be represented by KEYNOTFOUND.
@param first: Fist dictionary to diff.
@param second: Second dicationary to diff.
@return diff: Dict of Key => (first.val, second.val)
"""
diff = {}
# Check all keys in first dict
for key in first.keys():
if (not second.has_key(key)):
diff[key] = (first[key], KEYNOTFOUND)
elif (first[key] != second[key]):
diff[key] = (first[key], second[key])
# Check all keys in second dict to find missing
for key in second.keys():
if (not first.has_key(key)):
diff[key] = (KEYNOTFOUND, second[key])
return diff
you may temporarily transfer dic[2] to a set
in python, and use -
to get the difference
What about something like:
def diff(a,b):
ret_dict = {}
for key,val in a.items():
if b.has_key(key):
if b[key] != val:
ret_dict[key] = [val,b[key]]
else:
ret_dict[key] = [val]
for key,val in b.items():
ret_dict.setdefault(key,[val])
return ret_dict
That can be done in one line.
[b[k] for k in a.keys() if not k in b]
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