如何对复杂的 Python 列表进行排序？

Question

I have a complex list of events and times that I want to sort. I want to have the events listed by the start time, so an event on April 1st goes before an event on April 2nd.

The problem is, is that the events are sorted in a (weird?) list that looks like this:

all_events = [['My Event', 1588766400], 
              ['Cinco de Mayo', 1588636800], 
              ["Mother's Day", 1589068800], 
              ['Memorial Day', 1590364800], 
              ["Father's Day", 1592697600], 
              ['Independence Day observed', 1593734400], 
              ['Independence Day', 1593820800], 
              ['Tax Day', 1594771200], 
              ['Labor Day', 1599436800], 
              ['Columbus Day (regional holiday)', 1602460800], 
              ['Halloween', 1604102400]]

If you convert the epochs to RFC 2822, you can see the Cinco de Mayo is supposed to go first, then My Event. (I used https://coderstoolbox.net/unixtimestamp/ )

I would have taken the times from all_events to another list by doing

times = []

for event in all_events:
    times.append(event[1])

and then sort them using the Python sorted() function but then if I sort just the times, I wouldn't be able to keep track of the differences the the times list.

So is there a way to keep track of the differences in a list and apply the differences to another list? (Whoa, that was a mouthful)

Answer 1

Just sort by the time:

sorted(all_events, key=lambda event: event[1])

or if you want to make it more verbose/explicit/well-typed:

from typing import List, Union

Event = List[Union[int, str]]  # [name: str, time: int]

def get_event_time(event: Event) -> int:
    assert isinstance(event[1], int)
    return event[1]

sorted(all_events, key=get_event_time)