Calculate rarity score per ERC-721 items

[vikiival]

for ERC-721 add

rarity: Float!

after create was called:

• check if you indexed max
• calculate rarity on last fetched item

ref

• Sort by rarity in explorer nft-gallery#3181

articles:

• How to Calculate the Rarity of an NFT
• Understanding Rarity Calculation Methods

[vikiival]

First we need to change attribute schema from JSON to actual entity.

However it is hackable to do so via view

CREATE OR REPLACE view trait_list as
select
    x.acc ->> 'trait' trait,
    x.acc ->> 'value' "value",
    m.id
from metadata_entity m
cross join lateral jsonb_array_elements(m.attributes) as x(acc);

to get counts for attributes simply run

SELECT
    trait,
    value,
    count(value)
FROM
    trait_list
GROUP BY
    GROUPING SETS (
        (trait),
        (trait, value)
    );

this will tell you the counts for each trait-value and also total for each trait

to sum it up:

select
       trait,
       value,
       count(value),
       ROUND((count(value) / sum(count(value)) over (partition by trait)) * 100, 2) as rarity
    from trait_list
group by trait, value
order by value;

this will return:

• trait: hat,
• value: Black Unicorn
• count: 24
• rarity: count / total * 100 -> 5.02%

then we need to basically for each NFT calculate the avg rarity ∑(rarities) / trait_count

[vikiival]

This is imo most effective way to calculate it, may @dzlzv can have an opinion since he has PhD from math ;D

[yangwao]

opensea dropped openrarity