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// Copyright (C) 2015 The Android Open Source Project
//
// Licensed 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 charts
import "math"
func sum(vals []int) int {
v := 0
for _, x := range vals {
v += x
}
return v
}
func round(v float64) int {
if v < 0 {
return int(v - 0.5)
} else {
return int(v + 0.4999999)
}
}
func flooredPOT(v float64) int {
log2 := math.Log2(v)
if log2 >= 0 {
return int(1 << uint(log2))
} else {
return 1
}
}
func calculateStepInterval(multiple, valueRange, targetCount int) int {
return multiple * flooredPOT(float64(valueRange)/float64(targetCount*multiple))
}
func quantize(valueRange, targetCount int, multiples ...int) int {
best := 0
bestErr := math.MaxInt32
for _, m := range multiples {
step := calculateStepInterval(m, valueRange, targetCount)
err := int(valueRange) - int(step*targetCount)
if err < bestErr {
bestErr = err
best = step
}
}
return best
}
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