Converting List of 3 Element Tuple to Dictionary

Question

If I have two List of tuples

tuple2list=[(4, 21), (5, 10), (3, 8), (6, 7)]

tuple3list=[(4, 180, 21), (5, 90, 10), (3, 270, 8), (6, 0, 7)]

Answer 1

In Python2.7 or newer, you could use a dict comprehension:

In [100]: tuplelist = [(4, 180, 21), (5, 90, 10), (3, 270, 8), (4, 0, 7)]

In [101]: tuplelist2dict = {a:{b:c} for a,b,c in tuplelist}

In [102]: tuplelist2dict
Out[102]: {3: {270: 8}, 4: {0: 7}, 5: {90: 10}}

In Python2.6 or older, the equivalent would be

In [26]: tuplelist2dict = dict((a,{b:c}) for a,b,c in tuplelist)

Note that if the first value in the tuples occurs more than once, (as in the example above) the resulting tuplelist2dict only contains one key-value pair -- corresponding to the last tuple with the shared key.