mv code into src

src/learner/helper_utils.h

@@ -0,0 +1,50 @@
+#ifndef XGBOOST_LEARNER_HELPER_UTILS_H_
+#define XGBOOST_LEARNER_HELPER_UTILS_H_
+/*!
+ * \file helper_utils.h
+ * \brief useful helper functions
+ * \author Tianqi Chen, Kailong Chen
+ */
+#include <utility>
+#include <vector>
+#include <algorithm>
+namespace xgboost {
+namespace learner {
+// simple helper function to do softmax
+inline static void Softmax(std::vector<float>* p_rec) {
+  std::vector<float> &rec = *p_rec;
+  float wmax = rec[0];
+  for (size_t i = 1; i < rec.size(); ++i) {
+    wmax = std::max(rec[i], wmax);
+  }
+  double wsum = 0.0f;
+  for (size_t i = 0; i < rec.size(); ++i) {
+    rec[i] = std::exp(rec[i]-wmax);
+    wsum += rec[i];
+  }
+  for (size_t i = 0; i < rec.size(); ++i) {
+    rec[i] /= static_cast<float>(wsum);
+  }
+}
+// simple helper function to do softmax
+inline static int FindMaxIndex(const std::vector<float>& rec) {
+  size_t mxid = 0;
+  for (size_t i = 1; i < rec.size(); ++i) {
+    if (rec[i] > rec[mxid] + 1e-6f) {
+      mxid = i;
+    }
+  }
+  return static_cast<int>(mxid);
+}
+
+inline static bool CmpFirst(const std::pair<float, unsigned> &a,
+                            const std::pair<float, unsigned> &b) {
+  return a.first > b.first;
+}
+inline static bool CmpSecond(const std::pair<float, unsigned> &a,
+                             const std::pair<float, unsigned> &b) {
+  return a.second > b.second;
+}
+}  // namespace learner
+}  // namespace xgboost
+#endif  // XGBOOST_LEARNER_HELPER_UTILS_H_