CODEWITHSUNDEEP
pythonlistsplitsublist
papita_novana
papita_novana

Reputation: 53

How to split list of strings according to character in Python

I have got a list of strings like this:

org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc', 
        '<dialog xyz', 'string', 'more string', 'even more string etc']

I need to divide the list into sublists of strings, dividing them precisely on '<' character so that every sublist of strings begins with 'dialog xyz'. Sample output:

[['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog 
  xyz', 'string', 'more string', 'even more string etc']]

I already tried list comprehension but it does not work (returns the same org_list):

divided_list = [s.split(',') for s in ','.join(org_list).split('<')]

I know it is possible with itertools (saw it in some answers) but I am still a beginner, don't understand them much and would like to solve this with what I do understand, if possible.

Upvotes: 3

Views: 1638

Answers (8)

Aaditya Ura
Aaditya Ura

Reputation: 12669

You can do something like this:

org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc',
        '<dialog xyz', 'string', 'more string', 'even more string etc']



flag=True
sub_list=[]
final_list=[]
text='<dialog xyz'
for i in org_list:
    if i.startswith(text):


        flag=False

        if sub_list:
            sub_list.insert(0,text)
            final_list.append(sub_list)

            sub_list=[]

    else:
        if flag==False:



            sub_list.append(i)
sub_list.insert(0,text)
final_list.append(sub_list)
print(final_list)

output:

[['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog xyz', 'string', 'more string', 'even more string etc']]

Upvotes: 0

Mik
Mik

Reputation: 89

Сompetition. Who will make the function more difficult and slower. Be simpler, it is Python.

org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc', 
        '<dialog xyz', 'string', '', 'even more string etc' , '<dialog xyz', 'string', 'more string',]

def slicelist (pred, iterable):
    element = []
    alw = False
    for s in iterable:
         sw = s.startswith
         if sw(pred):
                element.append([])
                alw=True
         if alw :        
                element[-1].append(s)
    return element

print slicelist('<', org_list)

If you want to make generator(iterator), you need to change next operators in the above example : return to yield and print slicelist('<', org_list) to print list(slicelist('<', org_list))

Upvotes: 0

Ajax1234
Ajax1234

Reputation: 71451

You can use itertools.groupby:

import itertools
import re
org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc', 
    '<dialog xyz', 'string', 'more string', 'even more string etc']
new_list = [list(b) for a, b in itertools.groupby(filter(None, org_list), key=lambda x:bool(re.findall('^\<dialog', x)))]
final_list = [new_list[i]+new_list[i+1] for i in range(0, len(new_list), 2)]

Output:

[['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog xyz', 'string', 'more string', 'even more string etc']]

Upvotes: 0

Austin
Austin

Reputation: 26039

How about something simple like this:

org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc', '<dialog xyz', 'string', 'more string', 'even more string etc']
split_lists = [] 
for s in org_list:
  if s == '':
    continue
  if s.startswith('<') or len(split_lists) == 0: 
    split_lists.append([s])
    continue
  split_lists[-1].append(s)

print(split_lists)

Output:

[['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog xyz', 'string', 'more string', 'even more string etc']]

Upvotes: 1

Rakesh
Rakesh

Reputation: 82755

This might help

org_list = ['', '<dialog xyz', 'string', 'more string', 'even more string etc',
        '<dialog xyz', 'string', 'more string', 'even more string etc']

result = [i.split("|") if i.startswith("<") else ("<"+i).split("|") for i in "|".join(filter(None, org_list)).split("|<")]
print result

Output:

[['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog xyz', 'string', 'more string', 'even more string etc']]

Upvotes: 0

Joe Iddon
Joe Iddon

Reputation: 20414

First we can create a list of indexes referring to the positions in org_list where the string at that position starts with a '<'.

We can then iterate through these in a list-comp taking slices between each pair of indexes.

However, at the end, we notice that the last slice must go to the end of org_list, so we must concatenate a list containing the index of one over the end to capture this.

Hopefully you can see how that description translates into the following code.

inds = [i for i, s in enumerate(org_list) if '<' in s] + [len(org_list)]
div_l = [org_list[inds[i]:inds[i+1]] for i in range(len(inds)-1)]

which gives the desired output of:

[['<dialog xyz', 'string', 'more string', 'even more string etc'],
 ['<dialog xyz', 'string', 'more string', 'even more string etc']]

Upvotes: 1

MiniGunnR
MiniGunnR

Reputation: 5800

org_list = ['', '<dialog xyz', 'ztring', 'more ztring', 'even more string etc', '<dialog xyz', 'string', 'more string', 'even more string etc']

orig = []
start = False

new = []

for item in org_list:
    if item == '<dialog xyz' or item == org_list[-1]:
        if len(new) > 1:
            orig.append(new)
        new = []
        start = True
    if start:
        new.append(item)

print(orig)

This gives me the output that you want.

Upvotes: 0

AgvaniaRekuva
AgvaniaRekuva

Reputation: 615

This should work:

split_lists = []
for s in org_list:
    if s.startswith('<') or len(split_lists) == 0:
        split_lists.append([])
    split_lists[-1].append(s)

Here is the result for your input:

>>> split_lists
[[''], ['<dialog xyz', 'string', 'more string', 'even more string etc'], ['<dialog xyz', 'string', 'more string', 'even more string etc']]

If you want to ignore all the strings before the first string with that starts with '<', like the empty string that is the first element in your org_list, then use this:

split_lists = []
for s in org_list:
    if s.startswith('<'):
        split_lists.append([])
    if len(split_lists) == 0:
        continue
    split_lists[-1].append(s)

Upvotes: 0

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