Aggregation

Calculate summary values for grouped rows. Aggregation functions run on each group's leaf rows.

Built-in Aggregation Functions

Name	Description
sum	Sum of numeric values
min	Minimum numeric value
max	Maximum numeric value
extent	[min, max] tuple
mean	Average of numeric values
median	Median of numeric values
unique	Array of unique values
uniqueCount	Count of unique values
count	Number of rows

How to Use

columnHelper.accessor('salary', {
  header: 'Salary',
  aggregationFn: 'sum',
  aggregatedCell: ({ getValue }) => `Total: $${getValue().toLocaleString()}`,
})

Custom Aggregation

columnHelper.accessor('salary', {
  header: 'Salary',
  aggregationFn: (columnId, leafRows, childRows) => {
    const values = leafRows.map((row) => row.getValue<number>(columnId))
    return values.reduce((sum, val) => sum + val, 0) / values.length
  },
  aggregatedCell: ({ getValue }) => `Avg: $${getValue().toLocaleString()}`,
})

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