topKWeighted

Returns an array of the approximately most frequent values in the specified column. The resulting array is sorted in descending order of approximate frequency of values (not by the values themselves). Additionally, the weight of the value is taken into account.

See Also

• topK
• approx_top_k
• approx_top_sum

Syntax

topKWeighted(N)(column, weight)
topKWeighted(N, load_factor)(column, weight)
topKWeighted(N, load_factor, 'counts')(column, weight)

Parameters

• N — The number of elements to return. Default value: 10. UInt64
• load_factor — Optional. Defines, how many cells reserved for values. If uniq(column) > N * load_factor, result of topK function will be approximate. Default value: 3. UInt64
• counts — Optional. Defines whether the result should contain an approximate count and error value. Bool

Arguments

• column — The name of the column for which to find the most frequent values. - weight — The weight. Every value is accounted weight times for frequency calculation. UInt64

Returned value

Returns an array of the values with maximum approximate sum of weights. Array

Examples

Usage example

SELECT topKWeighted(2)(k, w) FROM
VALUES('k Char, w UInt64', ('y', 1), ('y', 1), ('x', 5), ('y', 1), ('z', 10));

┌─topKWeighted(2)(k, w)──┐
│ ['z','x']              │
└────────────────────────┘

With counts parameter

SELECT topKWeighted(2, 10, 'counts')(k, w)
FROM VALUES('k Char, w UInt64', ('y', 1), ('y', 1), ('x', 5), ('y', 1), ('z', 10));

┌─topKWeighted(2, 10, 'counts')(k, w)─┐
│ [('z',10,0),('x',5,0)]              │
└─────────────────────────────────────┘

Introduced in version 1.1.