I have a line of code in python2.7 that generates a dictionary of empty dictionaries:
values=[0,1,2,4,5,8]
value_dicts={x:{} for x in values}
which throws a syntax error when run on python2.6.
I can do the same thing using a for loop:
values_dicts={}
values=[0,1,2,4,5,8]
for value in values :
values_dicts[value]={}
values_dicts
Out[25]: {0: {}, 1: {}, 2: {}, 4: {}, 5: {}, 8: {}}
But that seems silly. Why does the list comprehension (in the first block) not work in python2.6?
You can use the dict() constructor:
value_dicts = dict((x, {}) for x in values)
This uses a generator expression that constructs (key, value) tuples, which the dict() constructor is happy to turn into a dictionary for you.
Demo:
>>> values=[0,1,2,4,5,8]
>>> dict((x, {}) for x in values)
{0: {}, 1: {}, 2: {}, 4: {}, 5: {}, 8: {}}
The syntax you used (a dict comprehension) was not introduced until Python 2.7 and Python 3, see PEP 274.
Depending on your intended use, you could also just use a defaultdict instead.
from collections import defaultdict
value_dicts = defaultdict(lambda: defaultdict(int))
