We just decided to add mood support to MB/LB. Now we need to decide which moods to use on the Arousal/Valence scale and come up with a simple graphic that outlines the two levels of moods we've discussed.

The list of choices should be limited to avoid being a confusing feature.
The basic 4 moods on Robert Thayer's valence-arousal diagram* (see image below) are:

• Angry
• Happy
• Sad
• Relaxed
  

I was thinking something along the lines of this diagram to also allow to select more nuanced moods:
(from the above image, I'm interested in the diagram type, not the contents of it)

• Some sources:

• "Music mood dataset creation based on Last.FM tags" (Çano and Morisio, 2017): http://hdl.handle.net/11583/2669975
• "Discussion on Mood Taxonomy": https://www.music-ir.org/mirex/wiki/2007:Previous_Discussion_on_Mood_Taxonomy
• "The IMIRSEL has derived a set of 5 mood clusters": https://www.music-ir.org/mirex/wiki/2007:Audio_Music_Mood_Classification#Mood_Categories (apparently validated by the MTG Barcelona
• "Detecting Emotion in Music" (Li and Ogihara, 2003): https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/41/paper.pdf