This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 8 years ago.
I have a list like:
l = [[1,2,3],[4,5]]
I would like to unpack each element to make it like:
l = [1,2,3,4,5]
I have my solution here:
l = reduce(lambda x, y: x+y, l)
Anyone has other Pythonic way? Thanks.
You should use itertools methods;
from itertools import chain
l = [[1,2,3],[4,5]]
list(chain.from_iterable(l))
Related
This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 2 years ago.
How to flatten the coordinates?
For input :[(1,2),(5,6),(7,8)]
expecting the output as [1,2,5,6,7,8]
Try it like this:
mylist = [(1,2),(5,6),(7,8)]
newlist = []
for x in mylist:
newlist += x
print(newlist)
from the itertools doc page
from itertools import chain
def flatten(listOfLists):
"Flatten one level of nesting"
return chain.from_iterable(listOfLists)
This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 3 years ago.
Currently I have a list of lists
l=[['asd'],['fgd']].
I want to turn it into a list
goal_list=['asd','fgd']
but I do not know how to turn a list into the value inside it - does anyone have an idea how to this efficiently?
This is a perfect use-case for itertools.chain, where we essentially chain all sublists together to flatten them!
from itertools import chain
def single_list(arr):
return list(chain(*arr))
print(single_list([['asd'],['fgd']]))
print(single_list([['asd', 'abcd'],['fgd', 'def']]))
The output will be
['asd', 'fgd']
['asd', 'abcd', 'fgd', 'def']
Just use a list comprehension with two loops:
goal_list = [item for sublist in l for item in sublist]
This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 6 years ago.
How do I convert a list of lists to a single list?
Input:
a=[['AA'], ['AE'], ['AH'], ['AO'],]
Desired output:
['AA','AE','AH','AO']
a=[['AA'], ['AE'], ['AH'], ['AO'],]
l=[]
for i in a:
l.extend(i)
print l
you could use comprehension list:
or using map and lambda functions
a=[['AA'], ['AE'], ['AH'], ['AO'],]
# open the item [0] with generators
Newa = [x[0] for x in a]
>>>['AA', 'AE', 'AH', 'AO']
see examples: http://www.secnetix.de/olli/Python/list_comprehensions.hawk
EDIT:
for i, value in enumerate(a):
a[i] = value[0]
This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 7 years ago.
Assume you have a list :
mylist=[[1,2,3,4],[2,3,4,5],[3,4,5,6]]
any pythonic(2.x) way to unpack the inner lists so that new list should look like ?:
mylist_n=[1,2,3,4,2,3,4,5,3,4,5,6]
import itertools
mylist=[[1,2,3,4],[2,3,4,5],[3,4,5,6]]
print list(itertools.chain(*mylist))
mylist_n = [j for i in mylist for j in i]
This question already has answers here:
How do I make a flat list out of a list of lists?
(34 answers)
Closed 7 years ago.
What is the cleanest way to implement the following:
list = [list1, list2, ...]
return [*list1, *list2, ...]
It looks like this syntax will be available in Python 3.5. In the meantime, what is your solution?
This is commonly written as:
[x for l in list for x in l]