Line data    Source code

       1              : import * as arrow from 'apache-arrow';
       2              : 
       3              : import type { FieldType } from './chart_spec_paths.js';
       4              : 
       5              : /// A column of the query result that the builder can encode
       6              : export interface ChartColumn {
       7              :     name: string;
       8              :     /// The Vega-Lite type that the builder picks when the column is encoded
       9              :     type: FieldType;
      10              :     /// The spec encodes the column but the result has no such column
      11              :     missing?: boolean;
      12              : }
      13              : 
      14              : /// The Vega-Lite type of an Arrow type: numbers are quantitative, dates and times temporal, the rest nominal
      15            1 : export function vegaLiteTypeOf(type: arrow.DataType): FieldType {
      16            1 :     switch (type.typeId) {
      17            1 :         case arrow.Type.Int:
      18            1 :         case arrow.Type.Int8:
      19            1 :         case arrow.Type.Int16:
      20            1 :         case arrow.Type.Int32:
      21            1 :         case arrow.Type.Int64:
      22            1 :         case arrow.Type.Uint8:
      23            1 :         case arrow.Type.Uint16:
      24            1 :         case arrow.Type.Uint32:
      25            1 :         case arrow.Type.Uint64:
      26            1 :         case arrow.Type.Float:
      27            1 :         case arrow.Type.Float16:
      28            1 :         case arrow.Type.Float32:
      29            1 :         case arrow.Type.Float64:
      30            1 :         case arrow.Type.Decimal:
      31            1 :             return 'quantitative';
      32            1 :         case arrow.Type.Date:
      33            1 :         case arrow.Type.DateDay:
      34            1 :         case arrow.Type.DateMillisecond:
      35            1 :         case arrow.Type.Timestamp:
      36            1 :         case arrow.Type.TimestampSecond:
      37            1 :         case arrow.Type.TimestampMillisecond:
      38            1 :         case arrow.Type.TimestampMicrosecond:
      39            1 :         case arrow.Type.TimestampNanosecond:
      40            1 :         case arrow.Type.Time:
      41            1 :         case arrow.Type.TimeSecond:
      42            1 :         case arrow.Type.TimeMillisecond:
      43            1 :         case arrow.Type.TimeMicrosecond:
      44            1 :         case arrow.Type.TimeNanosecond:
      45            1 :             return 'temporal';
      46            1 :         default:
      47            1 :             return 'nominal';
      48            1 :     }
      49            1 : }
      50              : 
      51              : /// The columns of the result, followed by the fields that the spec encodes but the result lacks.
      52              : /// Columns of the system, e.g. the row numbers of the cross filter, are not in the result schema.
      53            1 : export function chartColumns(schema: arrow.Schema | null, encodedFields: readonly string[]): ChartColumn[] {
      54            1 :     const columns: ChartColumn[] = (schema?.fields ?? []).map(field => ({ name: field.name, type: vegaLiteTypeOf(field.type) }));
      55              :     // Without a result, nothing is known to be missing
      56            1 :     if (schema == null) return encodedFields.map(name => ({ name, type: 'nominal' }));
      57            1 :     const names = new Set(columns.map(column => column.name));
      58            1 :     for (const name of encodedFields) {
      59            1 :         if (!names.has(name)) columns.push({ name, type: 'nominal', missing: true });
      60              :     }
      61            1 :     return columns;
      62            1 : }