Have to introduce new basis file format with names: make old format deprecated - like old solution format

Author: jajhall

check/TestCheckSolution.cpp

@@ -496,6 +496,50 @@ TEST_CASE("read-lp-file-solution", "[highs_check_solution]") {
   h.resetGlobalScheduler(true);
 }
 
+TEST_CASE("read-lp-file-basis", "[highs_check_solution]") {
+  const std::string test_name = Catch::getResultCapture().getCurrentTestName();
+  const std::string model_file_name = test_name + ".lp";
+  const std::string basis_file_name = test_name + ".bas";
+  const bool with_names = false;
+  HighsLp lp;
+  lp.num_col_ = 3;
+  lp.num_row_ = 2;
+  lp.col_cost_ = {0, 1, 1};
+  lp.col_lower_ = {0, 10, 0};
+  lp.col_upper_ = {kHighsInf, kHighsInf, kHighsInf};
+  if (with_names) lp.col_names_ = {"x", "y", "z"};
+  lp.row_lower_ = {1, -kHighsInf};
+  lp.row_upper_ = {kHighsInf, 2};
+  if (with_names) lp.row_names_ = {"r-lo", "r-up"};
+  lp.a_matrix_.start_ = {0, 2, 2, 4};
+  lp.a_matrix_.index_ = {0, 1, 0, 1};
+  lp.a_matrix_.value_ = {1, 1, 1, 1};
+  Highs h;
+  //  h.setOptionValue("output_flag", dev_run);
+  REQUIRE(h.passModel(lp) == HighsStatus::kOk);
+  h.run();
+  // Optimally x - basic; y - lower; z - lower
+  h.writeModel(model_file_name);
+  h.writeSolution("", 1);
+  h.writeBasis("");
+  h.writeBasis(basis_file_name);
+
+  h.readModel(model_file_name);
+  // Variables now ordered y; z; x
+  h.writeModel("");
+  h.readBasis(basis_file_name);
+  // Initial basis: y - basic; z - lower; x - lower, using basis for
+  // original ordering with new ordering. Not optimal - in fact basis
+  // matrix B = [0] is singular!
+  h.run();
+  REQUIRE(h.getInfo().simplex_iteration_count == 0);
+  
+  std::remove(model_file_name.c_str());
+  // std::remove(basis_file_name.c_str());
+  
+  h.resetGlobalScheduler(true);
+}
+
 void runWriteReadCheckSolution(Highs& highs, const std::string& test_name,
                                const std::string& model,
                                const HighsModelStatus require_model_status,

check/TestFilereader.cpp

@@ -496,17 +496,22 @@ TEST_CASE("handle-blank-space-names", "[highs_filereader]") {
   REQUIRE(h.writeSolution("", 1) == HighsStatus::kOk);
   REQUIRE(h.writeModel("") == HighsStatus::kOk);
 
-  lp.col_names_ = {"Column0", ""};
+  lp.col_names_ = {"Column", "Column"};
   lp.row_names_ = {"Row0", "Row1"};
   REQUIRE(h.passModel(lp) == HighsStatus::kOk);
+  REQUIRE(h.writeModel("") == HighsStatus::kError);
+
+  lp.col_names_ = {"Column0", ""};
+  REQUIRE(h.passModel(lp) == HighsStatus::kOk);
   h.run();
-  REQUIRE(h.writeSolution("") == HighsStatus::kOk);
+  REQUIRE(h.writeSolution("", -1) == HighsStatus::kOk);
   REQUIRE(h.writeModel("") == HighsStatus::kOk);
 
   std::vector<HighsInt> index = {0, 1};
   std::vector<double> value = {2, 3};
   REQUIRE(h.addRow(5, inf, 2, index.data(), value.data()) == HighsStatus::kOk);
   h.run();
+  REQUIRE(h.writeBasis("") == HighsStatus::kOk);
   REQUIRE(h.writeSolution("", 1) == HighsStatus::kOk);
   REQUIRE(h.writeModel("") == HighsStatus::kOk);
 

highs/lp_data/HighsModelUtils.cpp

@@ -417,47 +417,43 @@ HighsStatus normaliseNames(const HighsLogOptions& log_options,
     name_suffix = 0;
     names.resize(num_name_required);
     highsLogUser(log_options, HighsLogType::kWarning,
-                 "%6s names are blank or not present: using "
+                 "%s names are blank or not present: using "
                  "names with prefix \"%s\", beginning with suffix %d\n",
-                 column ? "Column" : "Row", name_prefix.c_str(), int(name_suffix));
+                 column ? "Column" : "Row   ", name_prefix.c_str(), int(name_suffix));
     for (HighsInt ix = 0; ix < num_name_required; ix++)
       names[ix] = name_prefix + std::to_string(name_suffix++);
     return HighsStatus::kOk;
   }
   names.resize(num_name_required);
-  // Form the hash table to check for duplicates
-  if (!name_hash.name2index.size()) name_hash.form(names);
-
+  HighsInt num_blank = 0;
+  const HighsInt from_name_suffix = name_suffix;
   for (HighsInt ix = 0; ix < num_name_required; ix++) {
     if (HighsInt(names[ix].length()) == 0) {
       // Name is blank, so create one
+      num_blank++;
       name_prefix = column ? kHighsUniqueColNamePrefix : kHighsUniquerowNamePrefix;
-      std::string name = name_prefix + std::to_string(name_suffix++);
-      auto search = name_hash.name2index.find(name);
-      if (search == name_hash.name2index.end()) {
-	// Name not found in hash, so replace blank name
-	names[ix] = name;
-	// Add name to hash, checking for duplicate
-	const bool duplicate =
-          !name_hash.name2index.emplace(name, ix).second;
-	assert(!duplicate);
-	assert(names[ix] == name);
-	assert(name_hash.name2index.find(name)->second == ix);
-      } else {
-	name_hash.name2index.clear();
-	return HighsStatus::kError;
-      }
-    } else {
-      size_t space_pos = names[ix].find(" ");
-      if (space_pos != std::string::npos) {
-	highsLogUser(log_options, HighsLogType::kError,
-		     "%s %d name \"%s\" contains a space character\n",
-		     column ? "Column" : "Row",
-		     int(ix), names[ix].c_str());
-	return HighsStatus::kError;
-      }
+      names[ix] = name_prefix + std::to_string(name_suffix++);
+    } else if (names[ix].find(" ") != std::string::npos) {
+      // Name contains a space, so return error
+      highsLogUser(log_options, HighsLogType::kError,
+		   "%s %d name \"%s\" contains a space character\n",
+		   column ? "Column" : "Row",
+		   int(ix), names[ix].c_str());
+      return HighsStatus::kError;
     }
   }
+  // Check for duplicates
+  if (name_hash.hasDuplicate(names)) {
+    name_hash.name2index.clear();
+    return HighsStatus::kError;
+  }
+  if (num_blank) 
+    highsLogUser(log_options, HighsLogType::kWarning,
+                 "Replaced %d blank %6s name%s by name%s with prefix \"%s\", beginning with suffix %d\n",
+		 int(num_blank), column ? "column" : "row",
+		 num_blank > 1 ? "s" : "",
+		 num_blank > 1 ? "s" : "",
+		 name_prefix.c_str(), int(from_name_suffix));
   return HighsStatus::kOk;
 }