printing a dictionary with specific format

Question

i am already done with my project and i want to print my results. i have a dictionary like this: {('a',): 4, ('b',): 5, ('c', 'd'): 3, ('e', 'f'): 4, ('g', 'h'): 3, ('i',): 3}

the key in some pair key-value is one element and in some others is two or three. and i want to print it in this format, the elements with one key in one line, the elements with two keys in a new line etc...

(elem,)
(elem1, elem2, ..., elem_n)

i tried this:

itemdct //my dict
result = [itemdct]
csv_writer = csv.writer(sys.stdout, delimiter=';')
row = []
for itemdct in result:
    for key in sorted(itemdct.keys()):
        row.append("{0}:{1}".format(key, itemdct[key]))
csv_writer.writerow(row)

but my output is like this in one line.

('a',):3;('b',):4;('c', 'd'):3;('e', 'f'):3;......

mydict is like this

{('a',): 3, ('b', 'c'): 3, ....}

and the result is like this

[{('a',): 3, ('b', 'c'): 3,.....}]

thank you in advance..

edit: i want my output to be like this:

('a',):3;('c',):4;('c',):5;('d',):6;('e',):3
('a', 'c'):3;('b', 'd'):3;('c', 'd'):4

Answer 1

Using itertools.groupby (one thing to note is that you have to sort first, because groupby will create a new group when the key value changes):

from itertools import groupby
d = {('a',): 4, ('b',): 5, ('c', 'd'): 3, ('e', 'f'): 4, ('g', 'h'): 3, ('i',): 3}
for i, g in groupby(sorted(d.items(), key = lambda k: len(k[0])), lambda k: len(k[0])):
  print(';'.join('%s:%s' %(k,v) for k,v in g))

## -- End pasted text --
('a',):4;('i',):3;('b',):5
('e', 'f'):4;('g', 'h'):3;('c', 'd'):3

ps I'm not sure what your assignment is, but you should probably not be using tuples as keys in a dictionary.

Answer 2

There is two steps to this. The first is to sort out what entry goes into what line, the other is to print those lines.

from collections import defaultdict

d = {('a',): 4, ('b',): 5, ('c', 'd'): 3, ('e', 'f'): 4, ('g', 'h'): 3, ('i',): 3}

keysize = defaultdict(list)
for key in d:
    keysize[len(key)].append("{}:{}".format(key, h[key]))

for size, line in keysize.iteritems():
    print ", ".join(line)

Answer 3

You can sort the items of your dictionary according to their key length. The you can use groupby to group by key length and print each group.

def printDict(myDict):
    from itertools import groupby
    def sortFunc(item):
        return len(item[0])

    sortedItems = sorted(myDict.items(), key=sortFunc)
    groups = groupby(sortedItems, sortFunc)
    for _, group in groups:         
        print( ';'.join('%s:%s' % entry for entry in group))

Output:

>>> printDict({('a',): 4, ('b',): 5, ('c', 'd'): 3, ('e', 'f'): 4, ('g', 'h'): 3, ('i',): 3})
('a',):4;('i',):3;('b',):5
('e', 'f'):4;('g', 'h'):3;('c', 'd'):3