How to split a list of tuples based on inner element value-CodePudding

I have a list of tuples of elements like this:

[
('All', 1, 0.6, 5.0),
('right,', 1, 0.6, 5.0),
("let's", 1, 0.6, 5.0),
('get', 0, 0.36, 5.0),
('the', 0, 0.36, 5.0),
('clock', 0, 0.36, 5.0),
('up', 0, 0.36, 5.0), 
('here.', 0, 0.36, 5.0)
]

I want to split this list into two lists whenever the 1st element changes. The result should be like this:

[
('All', 1, 0.6, 5.0),
('right,', 1, 0.6, 5.0),
("let's", 1, 0.6, 5.0)
],
[
('get', 0, 0.36, 5.0),
('the', 0, 0.36, 5.0),
('clock', 0, 0.36, 5.0),
('up', 0, 0.36, 5.0), 
('here.', 0, 0.36, 5.0)
]

What's the most pythonic way of doing this?

CodePudding user response：

mozway surely beat me but here's a solution that doesn't use libraries. It uses dictionaries!

lst = [...]    # contains your list

dct = {}

for tpl in lst: 
    idx = tpl[1]               # idx has the 'dependent' variable
    temp = dct.get(idx, [])
    temp.append(tpl)
    dct[idx] = temp
    
print(list(dct.values()))

print(dct.keys())

CodePudding user response：

This is a perfect use case for itertools.groupby:

Assuming the input list as l:

from itertools import groupby
[list(g) for k,g in groupby(l, lambda x: x[1])]

output:

[[('All', 1, 0.6, 5.0), ('right,', 1, 0.6, 5.0), ("let's", 1, 0.6, 5.0)],
 [('get', 0, 0.36, 5.0), ('the', 0, 0.36, 5.0), ('clock', 0, 0.36, 5.0), ('up', 0, 0.36, 5.0), ('here.', 0, 0.36, 5.0)]
]

CodePudding user response：

I used a list comprehension just to make it a single line statement.

Assumed that the entries change are 0 or 1.

lst = [
('All', 1, 0.6, 5.0),
('right,', 1, 0.6, 5.0),
("let's", 1, 0.6, 5.0),
('get', 0, 0.36, 5.0),
('the', 0, 0.36, 5.0),
('clock', 0, 0.36, 5.0),
('up', 0, 0.36, 5.0), 
('here.', 0, 0.36, 5.0)
]


new_lst = [[], []]

[new_lst[0].append(i) if i[1] == 0 else new_lst[1].append(i) for i in lst]

print(new_lst)

Output

[[('get', 0, 0.36, 5.0), ('the', 0, 0.36, 5.0), ('clock', 0, 0.36, 5.0), ('up', 0, 0.36, 5.0), ('here.', 0, 0.36, 5.0)], [('All', 1, 0.6, 5.0), ('right,', 1, 0.6, 5.0), ("let's", 1, 0.6, 5.0)]]