Python collections.defaultdict()

import collections
s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
d = collections.defaultdict(list)
for k, v in s:
print k, v
d[k].append(v)
print d
print list(d.items())

import collections
s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
# defaultdict
d = collections.defaultdict(list)
for k, v in s:
d[k].append(v)
# Use dict and setdefault
g = {}
for k, v in s:
g.setdefault(k, []).append(v)

# Use dict
e = {}
for k, v in s:
e[k] = v
##list(d.items())
##list(g.items())
##list(e.items())