improving music mood classification using lyrics, audio and social tags

unfolding repetitions as explained in Section 5.1.3). After these filtering criteria were applied,
there were 3,469 unique songs which form the positive example set.
5.2.2.3 Multi-label
Multi-label classification is relatively new in MIR, but in the mood dimension, it is more
realistic than single-label classification: This is evident in the dataset as there are many songs
that are members of more than one mood category. For example, the song, “I’ll Be Back” by
“The Beatles” is a positive example of the categories “calm” and “sad,” while the song, “Down
With the Sickness” by “Disturbed” is a positive example of the categories “angry,” “aggressive”
and “anxious.” Table 5.4 shows the distribution of songs belonging to multiple categories.
Table 5.4 Distribution of songs with multiple labels
Number of categories 1 2 3 4 5 6
Number of songs 1,639 1,010 539 205 62 14
Here an example is presented to illustrate how a song is labeled with these identified mood
categories. Figure 5.1 shows the most popular social tags on a song of “The Beatles,” “Here
Comes the Sun,” as published on last.fm on February 5th, 2010. Among these tags, eight match
the category terms listed in Table 5.3, and these terms belong to five categories as shown in
circles of the same colors. Therefore, this particular song is labeled as positive examples of these
five categories.
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