How to delete an element every 8 elements in a list of strings on python?

Question

Suppose that you have a list of strings like the following one:

the_list = ['02:00', '  GBP', '', 'Construction Output (MoM) (Jan)', '1.1%', '0.5%', '2.0%', '',
            '02:00', '  GBP', '', 'U.K. Construction Output (YoY) (Jan)', '9.9%', '9.2%', '7.4%', '',
            '02:00', '  GBP', '', 'GDP (MoM)', '0.8%', '0.2%', '-0.2%', '',
            '02:00', '  GBP', '', 'GDP (YoY)', '10.0%', '9.3%', '6.0%', '',
            '02:00', '  GBP', '', 'Index of Services', '1.0%', ' ', '1.2%', '']

Which every 8 elements appears '', which is an empty string, and it happens to be the same empty string that exists next to the one called GBP

How could the_list variable be updated so that it deletes the '' element that appears every 8 elements in the array of strings?

I just would like to know how can I delete the elements that are empty strings `''` except those that are next to the elements set as ` GBP` @OrkhanAliyev — NoahVerner, Mar 12 '22 at 00:33
One thing to note: it looks like you have gathered multiple rows of data into a single list. You should consider building this as a 2D list or a list of dictionaries or class objects to begin with which might make it easier to massage the format later. — Code-Apprentice, Mar 12 '22 at 01:00

score 3 · Accepted Answer · answered Mar 12 '22 at 00:48

If I understood you correctly, you can use list-comprehension to filter out the values at specific index:

new_list = [word for idx, word in enumerate(the_list, 1) if idx % 8 != 0]
print(new_list)

Prints:

['02:00', '  GBP', '', 'Construction Output (MoM) (Jan)', '1.1%', '0.5%', '2.0%',
 '02:00', '  GBP', '', 'U.K. Construction Output (YoY) (Jan)', '9.9%', '9.2%', '7.4%',
 '02:00', '  GBP', '', 'GDP (MoM)', '0.8%', '0.2%', '-0.2%',
 '02:00', '  GBP', '', 'GDP (YoY)', '10.0%', '9.3%', '6.0%',
 '02:00', '  GBP', '', 'Index of Services', '1.0%', ' ', '1.2%']

Incredible, I didn't know list-comprehension at all, but thank you so much for your answer, it definitely solved mi issue. I would also check that topic out, seems interesting . — NoahVerner, Mar 12 '22 at 00:53

score 0 · Answer 2 · answered Mar 12 '22 at 00:39

0

It's pretty simple:

del the_list[::8]  # or del the_list[7::8] if you try to delete the 7th element of each line

answered Mar 12 '22 at 00:39

Jonathan Dauwe

317
2
6

That would not achieve what the OP asked. – Alexander Mar 12 '22 at 00:51
1

@alexpdev actually, `del the_list[7::8] ` would work, but that's in a comment, but would be a decent answer to this question – juanpa.arrivillaga Mar 12 '22 at 00:53
@juanpa.arrivillaga Should the slice start at `2` instead of `7`? – Code-Apprentice Mar 12 '22 at 00:58
@Code-Apprentice no, because you want the item at index `7` to be the first item deleted, then every 8 items after that – juanpa.arrivillaga Mar 12 '22 at 00:59
To be precise, it's the difference between "delete every 8th element starting with the first element" versus "delete every 8th element starting with the 8th element" – juanpa.arrivillaga Mar 12 '22 at 01:00
@juanpa.arrivillaga Ok, ic...the OP wants to remove the last empty string in each "row", not the one starting at index 2 and repeating every 8. – Code-Apprentice Mar 12 '22 at 01:02

score -1 · Answer 3 · answered Mar 12 '22 at 00:43

-1

just use this code to find the element that you want to delete in that case is empty string, in python is a false string so

for x in the_list:
    if not x:
        the_list.remove(x)

answered Mar 12 '22 at 00:43

schtalman

112
3

That would also remove those empty/false strings that are next to ` GBP` strings, which is not desired – NoahVerner Mar 12 '22 at 00:45
just check the code, it would not remove that because this is part of the string – schtalman Mar 12 '22 at 00:49
1

And in general, this is a bug-prone approach that is highly inefficient. – juanpa.arrivillaga Mar 12 '22 at 00:50
Trying to remove items while iterating this way will not give what you expect, see https://stackoverflow.com/questions/1207406/how-to-remove-items-from-a-list-while-iterating – Thierry Lathuille Mar 12 '22 at 11:34

How to delete an element every 8 elements in a list of strings on python?

3 Answers3