From 964b58ae8302e0fadcceb982c92d49ab25538cd5 Mon Sep 17 00:00:00 2001
From: Chris Dyer <cdyer@cs.cmu.edu>
Date: Mon, 16 Apr 2012 18:37:04 -0400
Subject: improved alias sampler

---
 utils/alias_sampler.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/utils/alias_sampler.h b/utils/alias_sampler.h
index 85da9944..81541f7a 100644
--- a/utils/alias_sampler.h
+++ b/utils/alias_sampler.h
@@ -14,10 +14,13 @@
 // constructor computes the F's and L's given an arbitrary multionimial p in
 // O(n) time and Draw returns samples in O(1) time.
 struct AliasSampler {
-  explicit AliasSampler(const std::vector<double>& p) :
-      cutoffs_(p.size()),
-      aliases_(p.size(), std::numeric_limits<unsigned>::max()) {
+  AliasSampler() {}
+  explicit AliasSampler(const std::vector<double>& p) { Init(p); }
+  void Init(const std::vector<double>& p) {
     const unsigned N = p.size();
+    cutoffs_.resize(p.size());
+    aliases_.clear();
+    aliases_.resize(p.size(), std::numeric_limits<unsigned>::max());
     std::vector<unsigned> s,g;
     for (unsigned i = 0; i < N; ++i) {
       const double cutoff = cutoffs_[i] = N * p[i];
-- 
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