fix bug in the last commit.

src/io/bin.cpp

@@ -80,7 +80,7 @@ void BinMapper::FindBin(double* values, int num_sample_values, size_t total_samp
   std::sort(values, values + num_sample_values);
 
   // push zero in the front
-  if (num_sample_values || (values[0] > 0.0f && zero_cnt > 0)) {
+  if (num_sample_values == 0 || (values[0] > 0.0f && zero_cnt > 0)) {
     distinct_values.push_back(0.0f);
     counts.push_back(zero_cnt);
   }

src/io/dataset_loader.cpp

@@ -748,7 +748,7 @@ void DatasetLoader::ConstructBinMappersFromTextData(int rank, int num_machines,
         bin_type = BinType::CategoricalBin;
       }
       bin_mappers[i].reset(new BinMapper());
-      bin_mappers[i]->FindBin(sample_values[start[rank] + i].data(), static_cast<int>(sample_values[i].size()),
+      bin_mappers[i]->FindBin(sample_values[start[rank] + i].data(), static_cast<int>(sample_values[start[rank] + i].size()),
                               sample_data.size(), io_config_.max_bin, io_config_.min_data_in_bin, filter_cnt, bin_type);
     }
     // get max_bin