PyGotcha.py

#odd quirk found on Python
#say you have a list of values, and you want a dict with keys for each item, and each value an empty array.
#I found myself in this situation, and I decided to do it like this:
l = ['a','b','c']
gg = dict(zip(l,[[]]*3))
gg
#however, when you try and put a value into one of those arrays:
gg['a'].append(1)
gg
#1: {'a': [1], 'b': [1], 'c': [1]}
#the value is added to all 3!


gg = [[]]*5
gg
gg[0].append(1)
gg
#5: [[1], [1], [1], [1], [1]]

#the bastard
#I've now settled on the slightly less terse
gg = {i:[] for i in l}

#and now I don't know why in fuck I didn't do that in the first place