moon-phase.json

{
    "name": "Moon Phase",
    "description": "Extends a dataset with a data field to include the moon phase percentage and name.",
    "inputs": [
        {
            "name": "dataset-in",
            "type": "dataset-id",
            "description": "Dataset for extending with moon phase information."
        },
        {
            "name": "date-field",
            "type": "string",
            "description": "The name/id of the date field to use to calculate the moon phase."
        }
    ],
    "outputs": [
        {
            "name": "dataset-out",
            "type": "dataset-id",
            "description": "The ID of the extended dataset"
        }
    ]
}

moon-phase.whizzml

; Given a dataset and the name/id of a date field, this		
; extends the dataset with two new fields:		
;   The percentage of the moon phase new=0, full=50, new=100		
;   The name of the phase		
; The phase is computed by modular division of the lunar phase
; from the UNIX epoch, and is therefore useless for dates before Jan 1, 1970

(define (moon-phase dataset-in date-field) 
  (create-and-wait-dataset {
    "origin_dataset" dataset-in 
    "new_fields" [ 
     {
      "field" ( flatline "( / ( mod ( - ( / ( epoch ( field {{date-field}} )) 1000 ) 621300 ) 2551443 ) 2551442 )" )
      "name" "Moon Phase%"
     }, 
     {
      "field" ( flatline "( let ( pp ( / ( mod ( - ( / ( epoch ( field {{date-field}} )) 1000 ) 621300 ) 2551443 ) 2551442 )) ( cond ( < pp .05 ) \"New\" ( < pp .20 ) \"Waxing Crescent\" ( < pp .30 ) \"First Quarter\" ( < pp .45 ) \"Waxing Gibbous\" ( < pp .55 ) \"Full\" ( < pp .70 ) \"Waning Gibbous\" ( < pp .80 ) \"Third Quarter\" ( < pp .95 ) \"Waning Crescent\" \"New\" ))" )
      "name" "Moon Phase"
     }
    ]
  })
)

(define dataset-out (moon-phase dataset-in date-field))