/
items_sketch_partition_boundaries.go
63 lines (58 loc) · 2.32 KB
/
items_sketch_partition_boundaries.go
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package kll
import "errors"
type ItemsSketchPartitionBoundaries[C comparable] struct {
totalN uint64 //totalN of source sketch
boundaries []C //quantiles at the boundaries
natRanks []int64 //natural ranks at the boundaries
normRanks []float64 //normalized ranks at the boundaries
maxItem C //of the source sketch
minItem C //of the source sketch
inclusive bool //of the source sketch query to getPartitionBoundaries.
//computed
numDeltaItems []int64 //num of items in each part
numPartitions int //num of partitions
}
func newItemsSketchPartitionBoundaries[C comparable](totalN uint64, boundaries []C, natRanks []int64, normRanks []float64, maxItem C, minItem C, inclusive bool) (*ItemsSketchPartitionBoundaries[C], error) {
if len(boundaries) < 2 {
return nil, errors.New("boundaries must have at least 2 items")
}
numDeltaItems := make([]int64, len(boundaries))
numDeltaItems[0] = 0
for i := 1; i < len(boundaries); i++ {
addOne := 0
if (i == 1 && inclusive) || (i == len(boundaries)-1 && !inclusive) {
addOne = 1
}
numDeltaItems[i] = natRanks[i] - natRanks[i-1] + int64(addOne)
}
return &ItemsSketchPartitionBoundaries[C]{
totalN: totalN,
boundaries: boundaries,
natRanks: natRanks,
normRanks: normRanks,
maxItem: maxItem,
minItem: minItem,
inclusive: inclusive,
numDeltaItems: numDeltaItems,
numPartitions: len(boundaries) - 1,
}, nil
}
func (b *ItemsSketchPartitionBoundaries[C]) GetBoundaries() []C {
return b.boundaries
}