I was curios about the question: Eliminate consecutive duplicates of list elements, and how it should be implemented in Python.
What I came up with is this:
Plenty of better/more pythonic answers above, however one could also accomplish this task using list.pop()
:
my_list = [1, 2, 3, 3, 4, 3, 5, 5]
for x in my_list[:-1]:
next_index = my_list.index(x) + 1
if my_list[next_index] == x:
my_list.pop(next_index)
outputs
[1, 2, 3, 4, 3, 5]
Oneliner in pure Python
[v for i, v in enumerate(your_list) if i == 0 or v != your_list[i-1]]
>>> L = [1,1,1,1,1,1,2,3,4,4,5,1,2]
>>> from itertools import groupby
>>> [x[0] for x in groupby(L)]
[1, 2, 3, 4, 5, 1, 2]
If you wish, you can use map instead of the list comprehension
>>> from operator import itemgetter
>>> map(itemgetter(0), groupby(L))
[1, 2, 3, 4, 5, 1, 2]
For the second part
>>> [x for x, y in groupby(L) if len(list(y)) < 2]
[2, 3, 5, 1, 2]
If you don't want to create the temporary list just to take the length, you can use sum over a generator expression
>>> [x for x, y in groupby(L) if sum(1 for i in y) < 2]
[2, 3, 5, 1, 2]
To Eliminate consecutive duplicates of list elements; as an alternative, you may use itertools.zip_longest() with list comprehension as:
>>> from itertools import zip_longest
>>> my_list = [1,1,1,1,1,1,2,3,4,4,5,1,2]
>>> [i for i, j in zip_longest(my_list, my_list[1:]) if i!=j]
[1, 2, 3, 4, 5, 1, 2]
Here is a solution without dependence on outside packages:
list = [1,1,1,1,1,1,2,3,4,4,5,1,2]
L = list + [999] # append a unique dummy element to properly handle -1 index
[l for i, l in enumerate(L) if l != L[i - 1]][:-1] # drop the dummy element
Then I noted that Ulf Aslak's similar solution is cleaner :)
You can do this by using zip_longest()
+ list comprehension.
from itertools import zip_longest
list1 = [1, 2, 3, 3, 4, 3, 5, 5].
# using zip_longest()+ list comprehension
res = [i for i, j in zip_longest(list1, list1[1:])
if i != j]
print ("List after removing consecutive duplicates : " + str(res))