I want to split the following list into sub lists based on an element from that list.
array=['first','sentence','step','second','sentence']
for i in array:
if i!='step':
newlist1.append(i)
else:
(stop appending in newlist1 and start appending in say newlist2)
newlist1 and newlist2 can not be pre declared. As the number of elements in the array can vary. SO I need to find a dynamic way of declaring lists as per the requirement.
you could use a list of lists to store these. So if the value is step then start a new list, if not then append to the last list.
from pprint import pprint
lists = [[]]
array = ['first', 'sentence', 'step', 'second', 'sentence', 'step', 'thrid', 'step', 'some', 'other', 'sentance']
for i in array:
if i == 'step':
lists.append([])
else:
lists[-1].append(i)
pprint(lists)
OUTPUT
[['first', 'sentence'],
['second', 'sentence'],
['thrid'],
['some', 'other', 'sentance']]
You can do the following:
array=['first','sentence','step','second','sentence']
newlist1 = []
newlist2 = []
check = True
for i in array:
if i!='step' and check:
newlist1.append(i)
else:
check = False
newlist2.append(i)
Try this
index = array.index('step')
if index and index < len(array):
newlist1 = array[0:index+1]
newlist2 = array[index+1:]
Although less memory efficient than Chris Doyle's answer, I prefer comprehensions for stuff like this unless they get too verbose to fit on one line.
array = ['first', 'sentence', 'step', 'second', 'sentence', 'step', 'third', 'step', 'some', 'other', 'sentence']
def split_list(lst, sep):
return [i.split() for i in ' '.join(lst).split(sep)]
print(split_list(array, 'step'))
Result
[['first', 'sentence'], ['second', 'sentence'], ['third'], ['some', 'other', 'sentence']]
Bonus
If the end goal is a list of sentences instead of a list of lists, just replace the first .split() with .strip().
[i.strip() for i in ' '.join(lst).split(sep)]
Returns:
['first sentence', 'second sentence', 'third', 'some other sentence']
