append values in a list without sorting python, keeping the appending order

Question

I am producing a list of list by this code, it is just a condition for a column of a dataframe named lvl or "Level", then append the index of this condition values, so the problem that i got is that the order of appending is important to me,

for i in range(1,int(24-lvl)): j=list2[(list2.lvl==(lvl+i))] jj=[] jj.append(j.index) print itertools.chain(jj)

well for example, the answer should be: [0,100,110,500,501,550,555,89,120,114] but i get the same list but sorted [0,89,100,110,114,120,500,501,550,555]

score 3 · Answer 1 · answered Dec 23 '15 at 13:46

3

itertools.chain works for me. You need to unpack the list before passing it to chain method.

>>> l = [[1,5],[10,2],[6,9,3]]
>>> list(itertools.chain(*l))
[1, 5, 10, 2, 6, 9, 3]

answered Dec 23 '15 at 13:46

Avinash Raj

172,303
28
230
274

Or, better, use `itertools.chain.from_iterable(l)`. – taleinat Dec 23 '15 at 13:51
check this out http://imgur.com/1apSyZw it still results as an ordered list this are the original values that i am working – jmparejaz Dec 23 '15 at 14:01
1

You use Int64Index maybe you should add some tags like panda ? – Seif Dec 23 '15 at 14:09

score 0 · Answer 2 · answered Dec 23 '15 at 13:52

0

You can simply do it with list comprehension:

>>> l = [[1,5],[10,2],[6,9,3]]
>>> l_out = [item for sub_l in l for item in sub_l]
>>> l_out
[1, 5, 10, 2, 6, 9, 3]

answered Dec 23 '15 at 13:52

Iron Fist

10,739
2
18
34

check this out imgur.com/1apSyZw it still results as an ordered list this are the original values that i am working – jmparejaz Dec 23 '15 at 14:03
Why the down vote?..Express the cause behind it so I can fix my answer... – Iron Fist Dec 23 '15 at 14:56
1

i didnt downvote bro :( I found out what was the problem, – jmparejaz Dec 23 '15 at 15:07

append values in a list without sorting python, keeping the appending order

2 Answers2