1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <random>
#include <vespa/eval/eval/function.h>
using vespalib::make_string;
using vespalib::eval::Function;
//-----------------------------------------------------------------------------
class Model
{
private:
std::mt19937 _gen;
size_t _less_percent;
size_t get_int(size_t min, size_t max) {
std::uniform_int_distribution<size_t> dist(min, max);
return dist(_gen);
}
double get_real(double min, double max) {
std::uniform_real_distribution<double> dist(min, max);
return dist(_gen);
}
std::string make_feature_name() {
size_t max_feature = 2;
while ((max_feature < 1024) && (get_int(0, 99) < 55)) {
max_feature *= 2;
}
return make_string("feature_%zu", get_int(1, max_feature));
}
std::string make_cond() {
if (get_int(1,100) > _less_percent) {
return make_string("(%s in [%g,%g,%g])",
make_feature_name().c_str(),
get_int(0, 4) / 4.0,
get_int(0, 4) / 4.0,
get_int(0, 4) / 4.0);
} else {
return make_string("(%s<%g)",
make_feature_name().c_str(),
get_real(0.0, 1.0));
}
}
public:
explicit Model(size_t seed = 5489u) : _gen(seed), _less_percent(80) {}
Model &less_percent(size_t value) {
_less_percent = value;
return *this;
}
std::string make_tree(size_t size) {
assert(size > 0);
if (size == 1) {
return make_string("%g", get_real(0.0, 1.0));
}
size_t pivot = get_int(1, size - 1);
return make_string("if(%s,%s,%s)",
make_cond().c_str(),
make_tree(pivot).c_str(),
make_tree(size - pivot).c_str());
}
std::string make_forest(size_t num_trees, size_t tree_sizes) {
assert(num_trees > 0);
vespalib::string forest = make_tree(tree_sizes);
for (size_t i = 1; i < num_trees; ++i) {
forest.append("+");
forest.append(make_tree(tree_sizes));
}
return forest;
}
};
//-----------------------------------------------------------------------------
struct ForestParams {
size_t model_seed;
size_t less_percent;
size_t tree_size;
ForestParams(size_t model_seed_in, size_t less_percent_in, size_t tree_size_in)
: model_seed(model_seed_in), less_percent(less_percent_in), tree_size(tree_size_in) {}
};
//-----------------------------------------------------------------------------
Function make_forest(const ForestParams ¶ms, size_t num_trees) {
return Function::parse(Model(params.model_seed)
.less_percent(params.less_percent)
.make_forest(num_trees, params.tree_size));
}
//-----------------------------------------------------------------------------
|
