从列表中删除特定关键字之前的项目

Question

We scraped website data into a list with many irrelevant data in the beginning. How do we delete rows containing strings and floats until a specific keyword upon which it should keep the data in the list. For example:

We call our list ls with values like this:

None
bla2 
'11111.3434'
bla3
'1.43'
**Keyword** 
'1.43332'
Bla 4

We want to delete everything before the keyword and keep everything after the keyword in the same list structure.

It might be a very easy task, but we're just getting started with Python and got stuck with this part and couldn't find a suitable answer yet.

Thank you in advance!

Answer 1

Use list.index() to get the index, and del to delete

l = [None, 'bla2', '11111.3434', 'bla3', '1.43', 'Keyword', '1.43332','Bla 4']
del l[0: l.index('Keyword')]

print(l)

['Keyword', '1.43332', 'Bla 4']

Answer 2

You can use itertools.dropwhile :

import itertools
l = list(itertools.dropwhile(l, lambda i: i!=keyword))

Or you can use any filtering expression you like for the lambda.

Answer 3

Can try using slicing the list, an example can be this one

filter_list = lambda string_list, target_keyword: string_list[string_list.index(target_keyword)+1:]

After only need to call the method to perform the filter like this:

your_var = filter_list(x, 'Keyword')

Full example code

x = [None, 'bla2', 'test3', 'qweqw', 'eje', 'bu']

filter_list = lambda string_list, target_keyword: string_list[string_list.index(target_keyword)+1:]

print(filter_list(x, 'test3'))

Answer 4

since you didn't mention that the key word can repeat itself it can be done with a single for loop

ls = [None, 'bla2', '11111.3434', 'bla3', '1.43', 'imakeyword', '1.43332', 'Bla4']
keyword = 'imakeyword'
for item in ls:
    if item == keyword:
        pos = ls.index(item)
        new_ls = ls[pos:]

print(new_ls)