Merge pull request #20941 from vespa-engine/havardpe/handle-nan-in-tensor-spec-to-expr

handle nan cells when converting tensor spec to expression

2 files changed, 31 insertions, 2 deletions

diff --git a/eval/src/tests/eval/tensor_spec/tensor_spec_test.cpp b/eval/src/tests/eval/tensor_spec/tensor_spec_test.cpp
index 4c5b847abc1..6023d472d13 100644
--- a/eval/src/tests/eval/tensor_spec/tensor_spec_test.cpp
+++ b/eval/src/tests/eval/tensor_spec/tensor_spec_test.cpp
@@ -7,6 +7,10 @@
 using vespalib::Slime;
 using vespalib::eval::TensorSpec;
 
+auto my_nan = std::numeric_limits<double>::quiet_NaN();
+auto my_neg_inf = (-1.0/0.0);
+auto my_inf = (1.0/0.0);
+
 TEST("require that a tensor spec can be converted to and from slime") {
     TensorSpec spec("tensor(x[2],y{})");
     spec.add({{"x", 0}, {"y", "xxx"}}, 1.0)
@@ -30,6 +34,17 @@ TEST("require that a tensor spec can be converted to and from an expression") {
     EXPECT_EQUAL(TensorSpec::from_expr(expr), spec);
 }
 
+TEST("require that nan/inf/-inf cells get converted to valid expressions") {
+    TensorSpec spec("tensor<float>(x[2],y{})");
+    spec.add({{"x", 0}, {"y", "xxx"}}, my_nan)
+        .add({{"x", 0}, {"y", "yyy"}}, my_nan)
+        .add({{"x", 1}, {"y", "xxx"}}, my_neg_inf)
+        .add({{"x", 1}, {"y", "yyy"}}, my_inf);
+    vespalib::string expr = spec.to_expr();
+    fprintf(stderr, "expr: \n%s\n", expr.c_str());
+    EXPECT_EQUAL(TensorSpec::from_expr(expr), spec);
+}
+
 TEST("require that tensor specs can be diffed") {
     TensorSpec expect("tensor(x[2],y{})");
     expect.add({{"x", 0}, {"y", "xxx"}}, 1.5)
diff --git a/eval/src/vespa/eval/eval/tensor_spec.cpp b/eval/src/vespa/eval/eval/tensor_spec.cpp
index 025f3e8c0a3..223e32ce04f 100644
--- a/eval/src/vespa/eval/eval/tensor_spec.cpp
+++ b/eval/src/vespa/eval/eval/tensor_spec.cpp
@@ -19,6 +19,20 @@ namespace eval {
 
 namespace {
 
+vespalib::string number_to_expr(double value) { 
+    if (std::isfinite(value)) {
+        return make_string("%g", value);
+    } else if (std::isnan(value)) {
+        return {"(0/0)"};
+    } else { // -inf or inf
+        if (value < 0) {
+            return {"(-1/0)"};
+        } else {
+            return {"(1/0)"};
+        }
+    }
+}
+
 TensorSpec::Address extract_address(const slime::Inspector &address) {
     struct Extractor : slime::ObjectTraverser {
         TensorSpec::Address address;
@@ -288,14 +302,14 @@ vespalib::string
 TensorSpec::to_expr() const
 {
     if (_type == "double") {
-        return make_string("%g", as_double());
+        return number_to_expr(as_double());
     }
     vespalib::string out = _type;
     out.append(":{");
     CommaTracker cell_list;
     for (const auto &cell: _cells) {
         cell_list.maybe_add_comma(out);
-        out.append(make_string("%s:%g", as_string(cell.first).c_str(), cell.second.value));
+        out.append(make_string("%s:%s", as_string(cell.first).c_str(), number_to_expr(cell.second.value).c_str()));
     }
     out.append("}");
     return out;