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List help to split into single entries - Printable Version

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List help to split into single entries - paul41 - Nov-24-2019

I have a list which is in the following format:

list = ['A -> B', 'C -> D', 'E -> F']

I am trying to find a way to produce a list of single entries in the following format:

['A','B','C','D','E','F']

When I incorrectly attempt to split by using;

        newList = []
        for item in list:
            newList.append(item.split('->'))
        print(newList)
This incorrectly produces:

[['A','B], ['C','D'], ['E','F']]

Any help and advice would be greatly appreciated.

RE: List help to split into single entries - perfringo - Nov-24-2019

Never use list as a name. You overwrite built-in datatype list.

You should use 'extend' instead of 'append':

>>> lst =  ['A -> B', 'C -> D', 'E -> F']
>>> new_list = []
>>> for item in lst:
...     new_list.extend(item.split(' -> '))
... 
>>> new_list
['A', 'B', 'C', 'D', 'E', 'F']


RE: List help to split into single entries - paul41 - Nov-24-2019

Thank you that was exactly what I was looking for and gives me the results I require. In my data set I seem to have some whitespace in some of the items. Do you know how i can remove this within the same for loop?

RE: List help to split into single entries - perfringo - Nov-25-2019

(Nov-24-2019, 04:31 PM)paul41 Wrote: In my data set I seem to have some whitespace in some of the items. Do you know how i can remove this within the same for loop?

If the whitespaces are around arrow then code above takes care of that (it breaks at ' -> '). If there are additional whitespaces (at the beginning or end) then they could be stripped:

>>> lst =  ['A -> B ', ' C -> D', ' E -> F ']                          # note spaces at start and end                                             
>>> new = []                                                                               
>>> for item in lst: 
...    new.extend(chunk.strip() for chunk in item.split(' -> ')) 
...                                                                                        
>>> new                                                                                    
['A', 'B', 'C', 'D', 'E', 'F']
>>> [chunk.strip() for item in lst for chunk in item.split(' -> ')]    # same result with list comprehension                      
['A', 'B', 'C', 'D', 'E', 'F']