FAQ: Sets - Set Intersection

This community-built FAQ covers the “Set Intersection” exercise from the lesson “Sets”.

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This exercise can be found in the following Codecademy content:

Learn Intermediate Python 3

FAQs on the exercise Set Intersection

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This is another solution for the 2nd checkpoint. It’s quite lengthy
for song, tag in song_data.items():
if len(set(tags_int) & set(tag)) != 0 and song not in user_recent_songs:
recommended_songs[song] = tag

for tag in tags_int: for key, values in song_data.items(): if tag in values and key not in user_recent_songs.keys(): recommended_songs[key] = values

This loop adds songs to recommended_songs if they have EITHER of the two tags, if anyone is interested. Test it out by adding:
‘Just The Synth’: [‘synth’, ‘and’, ‘some’, ‘other’, ‘tags’], ‘Just Electronic’: [‘electronic’, ‘and’, ‘some’, ‘other’, ‘tags’]
To the song_data dictionary.

I used a dictionary comprehension as below;

recommended_songs = {song : tags for (song, tags) in song_data.items() if set(tags) & tags_int if song not in user_recent_songs}

This takes advantage of the boolean property of a non-empty set (in this case the intersection of set(tags) and tags_int) returning True.


Not the most efficient way but I ended up using nested for loops.

for song in song_data: print("printing", song) for tag in song_data[song]: print("printing tag", tag) if tag in tags_int: print("printing tag in tags_int", tag) if song not in user_recent_songs: recommended_songs[song] = tag

^^ still cleared step 2. But when I took a look at the solution and ran that code I got a different answer when I printed out the recommended songs.

:clap: Very concise! I didn’t remember two ‘if’ statements can be used in a row. Nice, thanks.

This is an awesome solution! I was a bit puzzled at first because nowhere in the course mentioned that empty sets are falsy in a Boolean context. Great find!

I came with the almost exact same solution.

I tend to write more lines while learning so that I see every single step.

my solution is:

for key, val in song_data.items():
    val_int = tags_int & set(val)
    if len(val_int) > 0 and key not in user_recent_songs:
        recommended_songs[key] = val