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init check

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tqchen 2014-11-09 21:56:56 -08:00
parent 5561dd9cb0
commit 69874dc571
1 changed files with 8 additions and 13 deletions
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19
src/utils/quantile.h
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@ -222,20 +222,15 @@ class WQuantileSketch {
}; };
/*! /*!
* \brief intialize the quantile sketch, given the performance specification * \brief intialize the quantile sketch, given the performance specification
* \param maxn maximum number of data points can be encountered * \param maxn maximum number of data points can be feed into sketch
* \param eps accuracy level of summary * \param eps accuracy level of summary
*/ */
inline void Init(RType maxn, double eps) { inline void Init(size_t maxn, double eps) {
nlevel = 0; nlevel = std::max(ceil(maxn * eps), 1.0);
size_t b = std::max(floor(log2(eps * maxn) / eps), 8.0); limit_size = ceil(nlevel / eps);
// check for small n case // check invariant
while (b < maxn) { utils::Assert((1 << nlevel) * limit_size > maxn, "invalid init parameter");
nlevel = ceil(log2(maxn / b)) + 1; utils::Assert(nlevel <= limit_size * eps, "invalid init parameter");
if (nlevel < eps * b) break;
++b;
}
nlevel += 1;
limit_size = (b + 1) / 2 + 1;
// lazy reserve the space, if there is only one value, no need to allocate space // lazy reserve the space, if there is only one value, no need to allocate space
inqueue.resize(1); inqueue.resize(1);
qtail = 0; qtail = 0;