Change fenwick tree to accept uint32 to avoid extra copy
- Id
- cbc82d5867313830846e88126ffc7f18aa02c960
- Author
- Vladimir Mihailenco
- Commit time
- 2018-11-01T14:27:04+02:00
Modified Gopkg.lock
# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
[[projects]]
+ digest = "1:cf63454c1e81409484ded047413228de0f7a3031f0fcd36d4e1db7620c3c7d1b"
name = "github.com/leesper/go_rng"
packages = ["."]
+ pruneopts = ""
revision = "5344a9259b21627d94279721ab1f27eb029194e7"
[[projects]]
- name = "github.com/yourbasic/fenwick"
- packages = ["."]
- revision = "7cb325001daae879940edf7b19da8557a51ca5f7"
- version = "1.2.0"
-
-[[projects]]
branch = "master"
+ digest = "1:ad6d9b2cce40c7c44952d49a6a324a2110db43b4279d9e599db74e45de5ae80c"
name = "gonum.org/v1/gonum"
packages = [
"blas",
"lapack/gonum",
"lapack/lapack64",
"mat",
- "stat"
+ "stat",
]
+ pruneopts = ""
revision = "f0982070f509ee139841ca385c44dc22a77c8da8"
[solve-meta]
analyzer-name = "dep"
analyzer-version = 1
- inputs-digest = "8b5c3547492f54e6308956cf6dcb413342643e051eaa84297c64fc334646ecf7"
+ input-imports = [
+ "github.com/leesper/go_rng",
+ "gonum.org/v1/gonum/stat",
+ ]
solver-name = "gps-cdcl"
solver-version = 1
Modified Gopkg.toml
# [[override]]
# name = "github.com/x/y"
# version = "2.4.0"
-
-[[constraint]]
- version = "1.2.0"
- name = "github.com/yourbasic/fenwick"
Modified summary.go
"math"
"sort"
- "github.com/yourbasic/fenwick"
+ "github.com/caio/go-tdigest/internal/fenwick"
)
type summary struct {
// Reinitialize the prefixSum cache
if s.bitree.Len() >= len(s.counts) {
for i := idx; i < len(s.counts); i++ {
- s.bitree.Set(i, int64(s.counts[i]))
+ s.bitree.Set(i, s.counts[i])
}
} else {
s.rebuildFenwickTree()
}
func (s *summary) rebuildFenwickTree() {
- x := make([]int64, cap(s.counts))
- for i := 0; i < s.Len(); i++ {
- x[i] = int64(s.counts[i])
- }
- s.bitree = fenwick.New(x...)
+ s.bitree = fenwick.New(s.counts[:cap(s.counts)]...)
}
func (s summary) Floor(x float64) int {
s.counts[index] = count
s.adjustRight(index)
s.adjustLeft(index)
- s.bitree.Set(index, int64(count))
+ s.bitree.Set(index, count)
}
func (s *summary) adjustRight(index int) {
Created internal/fenwick/LICENSE
+BSD 2-Clause License
+
+Copyright (c) 2017, Stefan Nilsson
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Created internal/fenwick/README.md
+This is https://github.com/yourbasic/fenwick with int64 replaced with uint32 to avoid constructing temporary []int64 slice just for the lib.
Created internal/fenwick/list.go
+// Package fenwick provides a list data structure supporting prefix sums.
+//
+// A Fenwick tree, or binary indexed tree, is a space-efficient list
+// data structure that can efficiently update elements and calculate
+// prefix sums in a list of numbers.
+//
+// Compared to a common array, a Fenwick tree achieves better balance
+// between element update and prefix sum calculation – both operations
+// run in O(log n) time – while using the same amount of memory.
+// This is achieved by representing the list as an implicit tree,
+// where the value of each node is the sum of the numbers in that
+// subtree.
+//
+package fenwick
+
+// List represents a list of numbers with support for efficient
+// prefix sum computation. The zero value is an empty list.
+type List struct {
+ // The tree slice stores range sums of an underlying array t.
+ // To compute the prefix sum t[0] + t[1] + t[k-1], add elements
+ // which correspond to each 1 bit in the binary expansion of k.
+ //
+ // For example, this is how the sum of the 13 first elements
+ // in t is computed: 13 is 1101₂ in binary, so the elements
+ // at indices 1101₂ - 1, 1100₂ - 1, and 1000₂ - 1 are added;
+ // they contain the range sums t[12], t[8] + … t[11], and
+ // t[0] + … + t[7], respectively.
+ //
+ tree []uint32
+}
+
+// New creates a new list with the given elements.
+func New(n ...uint32) *List {
+ len := len(n)
+ t := make([]uint32, len)
+ copy(t, n)
+ for i := range t {
+ if j := i | (i + 1); j < len {
+ t[j] += t[i]
+ }
+ }
+ return &List{
+ tree: t,
+ }
+}
+
+// Len returns the number of elements in the list.
+func (l *List) Len() int {
+ return len(l.tree)
+}
+
+// Get returns the element at index i.
+func (l *List) Get(i int) uint32 {
+ sum := l.tree[i]
+ j := i + 1
+ j -= j & -j
+ for i > j {
+ sum -= l.tree[i-1]
+ i -= i & -i
+ }
+ return sum
+}
+
+// Set sets the element at index i to n.
+func (l *List) Set(i int, n uint32) {
+ n -= l.Get(i)
+ for len := len(l.tree); i < len; i |= i + 1 {
+ l.tree[i] += n
+ }
+}
+
+// Add adds n to the element at index i.
+func (l *List) Add(i int, n uint32) {
+ for len := len(l.tree); i < len; i |= i + 1 {
+ l.tree[i] += n
+ }
+}
+
+// Sum returns the sum of the elements from index 0 to index i-1.
+func (l *List) Sum(i int) uint32 {
+ var sum uint32
+ for i > 0 {
+ sum += l.tree[i-1]
+ i -= i & -i
+ }
+ return sum
+}
+
+// SumRange returns the sum of the elements from index i to index j-1.
+func (l *List) SumRange(i, j int) uint32 {
+ var sum uint32
+ for j > i {
+ sum += l.tree[j-1]
+ j -= j & -j
+ }
+ for i > j {
+ sum -= l.tree[i-1]
+ i -= i & -i
+ }
+ return sum
+}
+
+// Append appends a new element to the end of the list.
+func (l *List) Append(n uint32) {
+ i := len(l.tree)
+ l.tree = append(l.tree, 0)
+ l.tree[i] = n - l.Get(i)
+}