armamut

-- BigQuery Function to check if 8, 12, 13, 14 digit GTIN codes are valid.
-- https://www.gs1.org/services/how-calculate-check-digit-manually
CREATE OR REPLACE FUNCTION `project-name.dataset-name.is_gtin_valid`(gtin STRING) AS (
CASE WHEN LENGTH(gtin) = 8 AND
            MOD(10 - MOD(
              CAST(SUBSTR(gtin,  1, 1) AS INT64) * 3 +
              CAST(SUBSTR(gtin,  2, 1) AS INT64) * 1 +
              CAST(SUBSTR(gtin,  3, 1) AS INT64) * 3 +
              CAST(SUBSTR(gtin,  4, 1) AS INT64) * 1 +
              CAST(SUBSTR(gtin,  5, 1) AS INT64) * 3 +

armamut

def focal_loss_lgb(y_true, y_pred, alpha=0.25, gamma=1.0):
    # Alpha or (1-alpha)
    a = y_true * alpha + (1-y_true) * (1-alpha)
    # Sign
    s = y_true * 2 - 1
    # Gamma
    g = gamma
    
    # Prob.
    p = 1/(1+np.exp(-y_pred))