Intervaller specificerade enligt kolumnvärden i PostgreSQL

I SQL Server kan du göra det så här:

;WITH CTE AS(
SELECT ROW_NUMBER() OVER(PARTITION BY CAST(wavelength AS INT)-CAST(wavelength AS INT)%10 ORDER BY wavelength) AS ROW_ID,wavelength,reflectance FROM Your_Table
)

SELECT wavelength,reflectance FROM CTE WHERE ROW_ID=1

Hoppas det skulle hjälpa.