This document discusses three approaches to determining the similarity between playlists for the purpose of creating similar playlists. The first approach would not work because it compares sorted lists of artists by ID, which could produce a high correlation even if the actual artists were different. The second approach would work because it directly compares the top artists between lists and scores an exact match as +1, providing a measure of absolute similarity between lists. The third approach would also work and is more advanced because it retrieves a genre tag for each artist, compares the genre tags between lists, and scores based on genre similarity rather than only exact artist matches. This provides a measure of similarity based on music style rather than only identical artists.

1. 3 flow considerations
about implementing
similar playlists

2. WOULD NOT WORK:
compile the top X
(eg. 10) list of
artists of each
playlist
sort this top X list
by artist_ID
compare two of
these sorted lists
with Pearson
Correlation (=r)
r can range from -1 to 1,
where 0 is no linear correlation
and 1 & -1 are perfectly linear
if(abs(r)) = close to 1, high linear correlation
Wouldnt work because, if artist ID's differ just one, still there
would be high linear correlation, but music completely different

3. WOULD WORK:
compile the top X
(eg. 10) list of
artists of each
playlist
compare the X
members of List A
to the X members
of List B
foreach exact hit,
add a +1 to the
score
score can range from 0 to X,
where 0 is no similarity and X
is perfectly similar
if(score = close to X) we have a very similar list
a lists based upon absolute matching artists.

4. WOULD WORK ADVANCED:
compile the top X
(eg. 10) list of
artists of each
playlist retrieve single
Tag for each artist
(genre)
compare the X
Tags of List A to
the X Tags of List
B
foreach exact hit,
add a +1 to the
score
score can range from 0 to X,
where 0 is no similarity and X
is perfectly similar
if(score = close to X) we have a very similar list
in this case, lists based upon similar music styles,
instead of absolute matching artists.