List of Python go heavy

The problem is to go to the news ID in a list and go back to the weight to ensure that the order is not changed.

Intuitive approach

The simplest idea is to:

Copy CodeThe code is as follows:
ids = [1,2,3,3,4,2,3,4,5,6,1]
News_ids = []
For ID in IDs:
If ID not in News_ids:
News_ids.append (ID)

Print News_ids

It works, but it doesn't look cool enough.

With Set

Another solution is to use set:

Copy CodeThe code is as follows:
ids = [1,4,3,3,4,2,3,4,5,6,1]
ids = List (set (IDS))

This result is not maintained in the original order.

Sort by index again

Finally, this approach solves:

Copy CodeThe code is as follows:
ids = [1,4,3,3,4,2,3,4,5,6,1]
News_ids = List (set (IDS))
News_ids.sort (Ids.index)

Using Itertools.grouby

The article mentions Itertools.grouby from the beginning, which can be used if the list order is not considered:

Copy CodeThe code is as follows:
ids = [1,4,3,3,4,2,3,4,5,6,1]
Ids.sort ()
it = itertools.groupby (IDs)

For K, G in it:
Print K

The principle of itertools.groupby can be seen here: http://docs.python.org/2/library/itertools.html#itertools.groupby

Users add: With reduce

The Netizen reatlk the message to the other solution. I add and explain here:

Copy CodeThe code is as follows:
In [5]: ids = [1,4,3,3,4,2,3,4,5,6,1]

In [6]: func = lambda x,y:x if y in x else x + [y]

In [7]: Reduce (func, [[],] + IDs)
OUT[7]: [1, 4, 3, 2, 5, 6]

Above is the code I run in Ipython, where Lambda x,y:x if y in x else x + [y] is equivalent to lambda x,y:y in X and X or X+[y].

The idea is to turn IDs into [[], 1,4,3,......] and then take advantage of the features of reduce. Reduce explanation see here: http://docs.python.org/2/library/functions.html#reduce

List of Python go heavy