Python: Dictionary merge by updating but not overwriting if value exists

Question

If I have 2 dicts as follows:

d1 = {(\'unit1\',\'test1\'):2,(\'unit1\',\'test2\'):4}
d2 = {(\'unit1\',\'test1\'):2,(\'unit1\',\'test2\'):\'\'}

Answer 1

Python 2.7. Updates d2 with d1 key/value pairs, but only if d1 value is not None,'' (False):

>>> d1 = dict(a=1,b=None,c=2)
>>> d2 = dict(a=None,b=2,c=1)
>>> d2.update({k:v for k,v in d1.iteritems() if v})
>>> d2
{'a': 1, 'c': 2, 'b': 2}