Что-то простое, как это должно работать
outer = [[item[0] for item in inner] for inner in timecolumn]
При условии, что внутренние списки содержат только один элемент
Пример:
timecolumn = [[[19310]],
[[19310], [19460]],
[[19310], [19460], [19800]],
[[19310], [19460], [19800], [20260]],
[[19310], [19460], [19800], [20260], [20880]],
[[19310], [19460], [19800], [20260], [20880], [21190]],
[[19460]],
[[19460], [19800]],
[[19460], [19800], [20260]],
[[19460], [19800], [20260], [20880]],
[[19460], [19800], [20260], [20880], [21190]],
[[19800]],
[[19800], [20260]],
[[19800], [20260], [20880]],
[[19800], [20260], [20880], [21190]],
[[20260]],
[[20260], [20880]],
[[20260], [20880], [21190]],
[[20880]],
[[20880], [21190]],
[[21190]]
]
outer = [[item[0] for item in inner] for inner in timecolumn]
Выход:
$ python -i timecolumn.py
>>> outer
[[19310], [19310, 19460], [19310, 19460, 19800], [19310, 19460, 19800, 20260], [19310, 19460, 19800, 20260, 20880], [19310, 19460, 19800, 20260, 20880, 21190], [19460], [19460, 19800], [19460, 19800, 20260], [19460, 19800, 20260, 20880], [19460, 19800, 20260, 20880, 21190], [19800], [19800, 20260], [19800, 20260, 20880], [19800, 20260, 20880, 21190], [20260], [20260, 20880], [20260, 20880, 21190], [20880], [20880, 21190], [21190]]
>>>