處理兩個列表之間的差異的各種排列

Question

給定兩個列表todays_ids和baseline_ids ，我將使用以下內容來編譯它們之間的差異：

    # Status                     added_ids             removed_ids
    # No IDs removed, none added []                    []
    # IDs removed, none added    []                    [id1, id2, ..]
    # IDs added, IDs removed     [id1, id2, ..]        [id1, id2, ..]
    # IDs added, none removed    [id1, id2, ..]        []

    added_ids = [_id for id in todays_ids if _id not in baseline_ids]
    removed_ids = [_id for id in baseline_ids if _id not in todays_ids]

然后，我需要采取不同的操作，具體取決於任何給定執行的四種可能結果中的哪一種。 為簡單起見，讓我們假設在每種情況下我只需要打印所有相關的ID。

if len(added_ids) == 0 and len(removed_ids) > 0
   print 'No new ids'
   print 'The following ids were removed_ids:'
   for _id in removed_ids:
       print _id 

elif len(added_ids) > 0 and len(removed_ids) > 0
   print 'The following ids were added:'
   for _id in added_ids:
       print _id 
   print 'The following ids were removed:'
   for _id in removed_ids:
       print _id 

elif len(added_ids) > 0 and len(removed_ids) == 0
   print 'The following ids were added:'
   for _id in added_ids:
       print _id 
   print 'No ids removed'

else:
    print 'No ids added or removed'

顯然，這里有一些重復的工作（也許是在使用列表理解的差異設置中， 以及在隨后的邏輯中），而不必要的是。 如何改善？

Answer 1

如果長度的總和均為0，請說； 否則，對於每個列表，說它為空或列出其內容。

Answer 2

嘗試這個：

today_ids = ['id1', 'id2', 'id5']
base_line_ids = ['id1','id2','id3','id4']

added_ids = set(today_ids).difference(base_line_ids)
removed_ids = set(base_line_ids).difference(today_ids)

# specific message for: no added, no removed
if set(today_ids) == set(base_line_ids):
    print('No ids added or removed')
    exit(0)

if len(removed_ids):
    print('The following ids were removed:\n{}'.format('\n'.join(removed_ids)))
else:
    print('No ids removed')

if len(added_ids):
    print('The following ids were added:\n{}'.format('\n'.join(added_ids)))
else:
    print('No ids added')

輸出：

The following ids were removed:
id4
id3
The following ids were added:
id5

Answer 3

added_ids = set(today_ids).difference(set(baseline_ids))
removed_ids = set(baseline_ids).difference(set(today_ids))

if added_ids:
    if removed_ids:
        do_something
    else:
        do_something
else:
    if removed_ids:
        do_something
    else:
        do_something