Question

我很难理解字典理解。我有一些代码需要检查轨道是否已从iTunes资料库中删除。如果有的话，我需要将其从特定的播放列表字典以及主曲目字典中删除。

我尝试使用下面的代码，但是它告诉我字典的大小在迭代过程中发生了变化。

我在阅读here和here时试图理解我如何以字典理解的方式来完成所有这些工作，但这却使我的大脑融化了。

# Next step is to ensure the track_id for a particular persistent_id is correct
# because iTunes can change the track_id of a track, but the persistent_id
# remains the same regardless of any track changes.
#
# Step through each playlist in the musicDict dictionary and update the
# persistentID with the correct trackID or delete the track data from the
# dictionary if it cannot be found in the itl

for playlistKey in musicDict['playlists'].keys():
   if 'tracks' in musicDict['playlists'][playlistKey]:
      for persistentID in musicDict['playlists'][playlistKey]['tracks'].keys():
         try:
            musicDict['playlists'][playlistKey]['tracks'][persistentID] = itl.byPID[persistentID].track_id # Track exists in itl
         except:
            del musicDict['playlists'][playlistKey]['tracks'][persistentID] # track no longer exists in itl
         if persistentID in musicDict['tracks'].keys() and persistentID not in itl.byPID.keys(): # check to see if the track needs to be deleted from the musicDict
            del musicDict['tracks'][persistentID] # delete the track since it no longer exists in itl

我正在使用libpytunes模块，并添加了另一个名为byPID的字典，因为track_id对于iTunes音乐不是保持静态，因此是persistentID变量和itl.byPID字典。

就像我在上面写的那样，这会产生一个错误（并且我理解为什么），并且我想将其转换为列表理解，或者如果理解不容易理解的话，可以将其转化为有效的for循环。

我该如何将所有这些综合起来？

0 个答案: