Fix Python – How to merge dicts, collecting values from matching keys?

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Question

Asked By – Salil

I have multiple dicts (or sequences of key-value pairs) like this:

d1 = {key1: x1, key2: y1}
d2 = {key1: x2, key2: y2}

How can I efficiently get a result like this, as a new dict?

d = {key1: (x1, x2), key2: (y1, y2)}

Now we will see solution for issue: How to merge dicts, collecting values from matching keys?

Answer

assuming all keys are always present in all dicts:

ds = [d1, d2]
d = {}
for k in d1.iterkeys():
    d[k] = tuple(d[k] for d in ds)

Note: In Python 3.x use below code:

ds = [d1, d2]
d = {}
for k in d1.keys():
  d[k] = tuple(d[k] for d in ds)

and if the dic contain numpy arrays:

ds = [d1, d2]
d = {}
for k in d1.keys():
  d[k] = np.concatenate(list(d[k] for d in ds))

This question is answered By – blubb

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