Question: I have a multi-dimensional list as like below

```
multilist = [[1,2],[3,4,5],[3,4,5],[5,6],[5,6],[5,6]]

```

How can I get below results fast:

```
[1,2]: count 1 times
[3,4,5]: count 2 times
[5,6]: count 3 times

```

and also get the unique multi-dimensional list (remove duplicates) :

```
multi_list = [[1,2],[3,4,5],[5,6]]

```

Thanks a lot.

Answer: 
As @ReutSharabani suggested, you can use tuples as dictionary keys, and then convert back to lists for display purposes. The code below doesn't reply on `collections` (not that there's anything wrong with that).

```
multilist = [[1,2],[3,4,5],[3,4,5],[5,6],[5,6],[5,6]]
histogram = {}
for x in multilist:
    xt = tuple(x)
    if xt not in histogram:
        histogram[xt] = 1
    else:
        histogram[xt] += 1
for k,c in histogram.items():
    print "%r: count %d times" % (list(k),c)
print [list(x) for x in histogram.keys()]

```
You can use a dictionary for this

```
count_data = {}

for my_list in multilist:
    count_data.setdefault(tuple(my_list), 0)
    count_data[tuple(my_list)] += 1

```