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Rendering Results

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When Malloy runs a query, it returns two things. The results of the query and metadata about the results. The metadata are the schema for the results, including type information. Malloy also provides a mechanism to tag things in the source code and return tags with this meta data.

In Malloy, anything that can be named can be tagged. A tag starts with a #. Tags that start on a new line attach the tag the thing on the following line. For more details about how tagging works, see the Tags section.

Malloy's rendering library interprets these tags to change how results are rendered.

Tagging individual elements

In the query below, the measure percent_of_total is tagged as a percentage. Any time percent_of_total is used in a query, Malloy's rendering library will be displayed as a percentage.

document
source: flights is duckdb.table('../data/flights.parquet') extend {
  measure:
    flight_count is count()
    # percent
    percent_of_flights is flight_count / all(flight_count)
}
document
run: flights -> {
  group_by: carrier
  aggregate: 
    flight_count 
    percent_of_flights
}
QUERY RESULTS 
[
  {
    "carrier": "WN",
    "flight_count": 88751,
    "percent_of_flights": 0.2573783375431738
  },
  {
    "carrier": "US",
    "flight_count": 37683,
    "percent_of_flights": 0.10928088577750582
  },
  {
    "carrier": "AA",
    "flight_count": 34577,
    "percent_of_flights": 0.10027347046489979
  },
  {
    "carrier": "NW",
    "flight_count": 33580,
    "percent_of_flights": 0.09738216554968143
  },
  {
    "carrier": "UA",
    "flight_count": 32757,
    "percent_of_flights": 0.09499546149228454
  },
  {
    "carrier": "DL",
    "flight_count": 32130,
    "percent_of_flights": 0.09317715840116929
  },
  {
    "carrier": "RU",
    "flight_count": 16074,
    "percent_of_flights": 0.046614679244954715
  },
  {
    "carrier": "MQ",
    "flight_count": 15869,
    "percent_of_flights": 0.046020178234302996
  },
  {
    "carrier": "EV",
    "flight_count": 15769,
    "percent_of_flights": 0.04573017774130216
  },
  {
    "carrier": "HP",
    "flight_count": 9750,
    "percent_of_flights": 0.028275048067581715
  },
  {
    "carrier": "AS",
    "flight_count": 8453,
    "percent_of_flights": 0.024513741673360845
  },
  {
    "carrier": "CO",
    "flight_count": 7139,
    "percent_of_flights": 0.020703135195329833
  },
  {
    "carrier": "B6",
    "flight_count": 4842,
    "percent_of_flights": 0.01404182387110058
  },
  {
    "carrier": "OH",
    "flight_count": 4420,
    "percent_of_flights": 0.012818021790637044
  },
  {
    "carrier": "TZ",
    "flight_count": 3033,
    "percent_of_flights": 0.00879571495271542
  }
]
WITH __stage0 AS (
  SELECT
    group_set,
    CASE WHEN group_set=1 THEN
      base."carrier"
      END as "carrier__1",
    CASE WHEN group_set=1 THEN
      COUNT(1)
      END as "flight_count__1",
    (CASE WHEN group_set=1 THEN
      COUNT(1)
      END)*1.0/MAX((CASE WHEN group_set=0 THEN
      COUNT(1)
      END)) OVER () as "percent_of_flights__1"
  FROM '../data/flights.parquet' as base
  CROSS JOIN (SELECT UNNEST(GENERATE_SERIES(0,1,1)) as group_set  ) as group_set
  GROUP BY 1,2
)
SELECT
  "carrier__1" as "carrier",
  MAX(CASE WHEN group_set=1 THEN "flight_count__1" END) as "flight_count",
  MAX(CASE WHEN group_set=1 THEN "percent_of_flights__1" END) as "percent_of_flights"
FROM __stage0
WHERE group_set NOT IN (0)
GROUP BY 1
ORDER BY 2 desc NULLS LAST
document
run: duckdb.table('../data/flights.parquet') ->  {
  group_by: carrier
  aggregate: flight_count is count()
}
QUERY RESULTS 
[
  {
    "carrier": "WN",
    "flight_count": 88751
  },
  {
    "carrier": "US",
    "flight_count": 37683
  },
  {
    "carrier": "AA",
    "flight_count": 34577
  },
  {
    "carrier": "NW",
    "flight_count": 33580
  },
  {
    "carrier": "UA",
    "flight_count": 32757
  },
  {
    "carrier": "DL",
    "flight_count": 32130
  },
  {
    "carrier": "RU",
    "flight_count": 16074
  },
  {
    "carrier": "MQ",
    "flight_count": 15869
  },
  {
    "carrier": "EV",
    "flight_count": 15769
  },
  {
    "carrier": "HP",
    "flight_count": 9750
  },
  {
    "carrier": "AS",
    "flight_count": 8453
  },
  {
    "carrier": "CO",
    "flight_count": 7139
  },
  {
    "carrier": "B6",
    "flight_count": 4842
  },
  {
    "carrier": "OH",
    "flight_count": 4420
  },
  {
    "carrier": "TZ",
    "flight_count": 3033
  }
]
SELECT 
   base."carrier" as "carrier",
   COUNT(1) as "flight_count"
FROM '../data/flights.parquet' as base
GROUP BY 1
ORDER BY 2 desc NULLS LAST

Simply adding # bar_chart before the query tags it and tells the rendering library to show the result as a bar chart. See the docs on the Bar Chart tag for more information.

document
# bar_chart
run: duckdb.table('../data/flights.parquet') ->  {
  group_by: carrier
  aggregate: flight_count is count()
}
QUERY RESULTS 
[
  {
    "carrier": "WN",
    "flight_count": 88751
  },
  {
    "carrier": "US",
    "flight_count": 37683
  },
  {
    "carrier": "AA",
    "flight_count": 34577
  },
  {
    "carrier": "NW",
    "flight_count": 33580
  },
  {
    "carrier": "UA",
    "flight_count": 32757
  },
  {
    "carrier": "DL",
    "flight_count": 32130
  },
  {
    "carrier": "RU",
    "flight_count": 16074
  },
  {
    "carrier": "MQ",
    "flight_count": 15869
  },
  {
    "carrier": "EV",
    "flight_count": 15769
  },
  {
    "carrier": "HP",
    "flight_count": 9750
  },
  {
    "carrier": "AS",
    "flight_count": 8453
  },
  {
    "carrier": "CO",
    "flight_count": 7139
  },
  {
    "carrier": "B6",
    "flight_count": 4842
  },
  {
    "carrier": "OH",
    "flight_count": 4420
  },
  {
    "carrier": "TZ",
    "flight_count": 3033
  }
]
SELECT 
   base."carrier" as "carrier",
   COUNT(1) as "flight_count"
FROM '../data/flights.parquet' as base
GROUP BY 1
ORDER BY 2 desc NULLS LAST

Malloy's renderering library uses the Vega-Lite for charting, allowing visualization of results. Malloy's rendering library is a separate layer from Malloy's data access layer.:

Rendering tags