common.cpp
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright 2012 The MITRE Corporation *
* *
* 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. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
#include "common.h"
using namespace std;
/**** GLOBAL ****/
void Common::seedRNG() {
static bool seeded = false;
if (!seeded) {
srand(0); // We seed with 0 instead of time(NULL) to have reproducible randomness
seeded = true;
}
}
QList<int> Common::RandSample(int n, int max, int min, bool unique)
{
seedRNG();
QList<int> samples; samples.reserve(n);
int range = max-min;
if (range <= 0) qFatal("Common::RandSample non-positive range.");
if (unique && (n >= range)) {
for (int i=min; i<max; i++)
samples.append(i);
return samples;
}
while (samples.size() < n) {
const int sample = (rand() % range) + min;
if (unique && samples.contains(sample)) continue;
samples.append(sample);
}
return samples;
}
QList<int> Common::RandSample(int n, const QSet<int> &values, bool unique)
{
seedRNG();
QList<int> valueList = values.toList();
if (unique && (values.size() <= n)) return valueList;
QList<int> samples; samples.reserve(n);
while (samples.size() < n) {
const int randIndex = rand() % valueList.size();
samples.append(valueList[randIndex]);
if (unique) valueList.removeAt(randIndex);
}
return samples;
}