The aim of this challenge is to implement a Class in Python to maintain an MP3 Playlist. This class could be used when developing the software for a music App on a smartphone or an mp3 player.
This MP3 playlist will be stored as a queue of MP3 tracks. When new tracks are being added to the playlist, they are enqueued at the end of the playlist. The key features that we will implement within this class are the ability to:
- Enqueue an MP3 to the playlist,
- Remove an MP3 from the playlist,
- Load a playlist from a text file,
- Save a playlist on a text file,
- Shuffle all the songs in the playlist,
- Display all the tracks from the playlist,
- Count the number of tracks in the playlist,
- Calculate the total duration of the playlist,
- Empty/Reset the playlist,
- Check if the playlist is empty.
Here is the class diagram for this project:
Python Code
We have started the code used to load a mp3 playlist from a text file.
Your task is to complete this code to implement all the methods mentioned above.
Solution (Step by step)
Here is the code to add to the Playlist class:
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def load(self): self.tracks = [] print("Loading tracks from CSV file.") file = open(self.filename,"r") for line in file: fields = line.split(";") track = Track(fields[0],fields[1],int(fields[2])) self.tracks.append(track) file.close() def save(self): print("Saving your playlist...") file = open(self.filename,"w") for track in self.tracks: file.write(track.title + ";" + track.artist + ";" + str(track.duration)+ ";") file.close() print("Playlist saved!") |
In the main program we can test our load() and save() methods using the following code:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() myPlaylist.view() #Add or remove tracks or shuffle the playlist... using the enqueue(), remove() and shuffle() methods. myPlaylist.save() |
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def enqueue(self, track): self.tracks.append(track) |
You can test this code as follows:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() newTrack = Track("Wonderwall","Oasis",245) myPlaylist.enqueue(newTrack) myPlaylist.view() myPlaylist.save() |
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def removeTrack(self, track): self.tracks.remove(track) |
You can test this code as follows:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() myPlaylist.view() myPlaylist.remove(myPlaylist.tracks[2]) #This will remove the third track from the playlist! myPlaylist.view() |
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def getNumberOfTracks(self): return len(self.tracks) |
To test this method:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() numberOfTracks = myPlaylist.getNumberOfTracks() print("This playlist has " + str(numberOfTracks) + " tracks!") |
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def getTotalDuration(self): duration = 0 for track in self.tracks: duration += track.duration return duration |
To test this method:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() duration = myPlaylist.getTotalDuration() print("This playlist lasts " + str(duration) + " seconds!") |
We will hence need to import the random library by adding the following line at the top of the playlist.py file:
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import random |
Then we will add the following method to the Playlist class:
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def shuffle(self): random.shuffle(self.tracks) |
In the main program we can test our shuffle method using the following code:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() myPlaylist.shuffle() myPlaylist.view() |
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def reset(self): self.tracks = [] |
In the main program we can test our reset method using the following code:
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() myPlaylist.reset() myPlaylist.view() |
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def isEmpty(self): return len(self.tracks)==0 |
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from playlist import Track, Playlist myPlaylist = Playlist("Pop Music","pop_music.csv") myPlaylist.load() if myPlaylist.isEmpty(): print("Your playlist is empty.") myPlaylist.reset() if myPlaylist.isEmpty(): print("Your playlist is empty.") myPlaylist.view() |
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