fix double to string precision (std::numeric_limits<double>::digits10 + 2)

include/LightGBM/utils/common.h

@@ -247,7 +247,7 @@ inline static std::string ArrayToString(const std::vector<T>& arr, char delimite
     return std::string("");
   }
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   str_buf << arr[0];
   for (size_t i = 1; i < arr.size(); ++i) {
     str_buf << delimiter;
@@ -262,7 +262,7 @@ inline static std::string ArrayToString(const std::vector<T>& arr, size_t n, cha
     return std::string("");
   }
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   str_buf << arr[0];
   for (size_t i = 1; i < std::min(n, arr.size()); ++i) {
     str_buf << delimiter;
@@ -312,7 +312,7 @@ inline static std::string Join(const std::vector<T>& strs, const char* delimiter
     return std::string("");
   }
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   str_buf << strs[0];
   for (size_t i = 1; i < strs.size(); ++i) {
     str_buf << delimiter;
@@ -329,7 +329,7 @@ inline static std::string Join(const std::vector<T>& strs, size_t start, size_t
   start = std::min(start, static_cast<size_t>(strs.size()) - 1);
   end = std::min(end, static_cast<size_t>(strs.size()));
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   str_buf << strs[start];
   for (size_t i = start + 1; i < end; ++i) {
     str_buf << delimiter;

src/io/tree.cpp

@@ -152,7 +152,7 @@ std::string Tree::ToString() {
 
 std::string Tree::ToJSON() {
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   str_buf << "\"num_leaves\":" << num_leaves_ << "," << std::endl;
 
   str_buf << "\"tree_structure\":" << NodeToJSON(0) << std::endl;
@@ -162,7 +162,7 @@ std::string Tree::ToJSON() {
 
 std::string Tree::NodeToJSON(int index) {
   std::stringstream str_buf;
-  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 1);
+  str_buf << std::setprecision(std::numeric_limits<double>::digits10 + 2);
   if (index >= 0) {
     // non-leaf
     str_buf << "{" << std::endl;

tests/python_package_test/test_basic.py

@@ -47,7 +47,7 @@ class TestBasic(unittest.TestCase):
         pred_from_model_file = bst.predict(X_test)
         self.assertEqual(len(pred_from_matr), len(pred_from_model_file))
         for preds in zip(pred_from_matr, pred_from_model_file):
-            self.assertAlmostEqual(*preds, places=15)
+            self.assertEqual(*preds)
 
 
 print("----------------------------------------------------------------------")