cspann: use brackets to format vectors

Postgres uses brackets to format vectors, e.g. [1, 2]. However, our test
code currently uses parentheses, e.g. (1, 2). Update our tests to use
brackets instead, so that we're more consistent.

Epic: CRDB-42943
Release note: None

Author: andy-kimball

pkg/sql/vecindex/cspann/index.go

@@ -1045,13 +1045,13 @@ type FormatOptions struct {
 // Format formats the vector index as a tree-formatted string similar to this,
 // for testing and debugging purposes:
 //
-// • 1 (4, 3)
+// • 1 [4, 3]
 // │
-// ├───• vec1 (1, 2)
-// ├───• vec2 (7, 4)
-// └───• vec3 (4, 3)
+// ├───• vec1 [1, 2]
+// ├───• vec2 [7, 4]
+// └───• vec3 [4, 3]
 //
-// Vectors with many dimensions are abbreviated like (5, -1, ..., 2, 8), and
+// Vectors with many dimensions are abbreviated like [5, -1, ..., 2, 8], and
 // values are rounded to 4 decimal places. Centroids are printed next to
 // partition keys.
 func (vi *Index) Format(
@@ -1091,7 +1091,7 @@ func (vi *Index) Format(
 					buf.WriteByte(' ')
 					utils.WriteVector(&buf, centroid, 4)
 				} else {
-					buf.WriteString(" (MISSING)\n")
+					buf.WriteString(" [MISSING]\n")
 				}
 				return nil
 			}
@@ -1109,9 +1109,9 @@ func (vi *Index) Format(
 		utils.WriteVector(&buf, original, 4)
 		details := partition.Metadata().StateDetails
 		if details.State != ReadyState {
-			buf.WriteString(" [")
+			buf.WriteString(" (")
 			buf.WriteString(details.String())
-			buf.WriteByte(']')
+			buf.WriteByte(')')
 		}
 		buf.WriteByte('\n')
 
@@ -1145,7 +1145,7 @@ func (vi *Index) Format(
 					buf.WriteByte(' ')
 					utils.WriteVector(&buf, refs[0].Vector, 4)
 				} else {
-					buf.WriteString(" (MISSING)")
+					buf.WriteString(" [MISSING]")
 				}
 				buf.WriteByte('\n')
 

pkg/sql/vecindex/cspann/index_test.go

@@ -854,24 +854,11 @@ func (s *testState) parseUseDataset(arg datadriven.CmdArg) vector.T {
 	return s.Dataset.At(s.parseInt(arg))
 }
 
-// parseVector parses a vector string in this form: (1.5, 6, -4).
+// parseVector parses a vector string in this form: [1.5, 6, -4].
 func (s *testState) parseVector(str string) vector.T {
-	// Remove parentheses and split by commas.
-	str = strings.TrimSpace(str)
-	str = strings.TrimPrefix(str, "(")
-	str = strings.TrimSuffix(str, ")")
-	elems := strings.Split(str, ",")
-
-	// Construct the vector.
-	vector := make(vector.T, len(elems))
-	for i, elem := range elems {
-		elem = strings.TrimSpace(elem)
-		value, err := strconv.ParseFloat(elem, 32)
-		require.NoError(s.T, err)
-		vector[i] = float32(value)
-	}
-
-	return vector
+	vec, err := vector.ParseVector(str)
+	require.NoError(s.T, err)
+	return vec
 }
 
 // parseKeyAndVector parses a line that may contain a key and vector separated
@@ -920,9 +907,9 @@ func (s *testState) loadIndexFromFormat(
 	// Parse centroid and state.
 	var details cspann.PartitionStateDetails
 	details.MakeReady()
-	idx = strings.Index(line, "[")
+	idx = strings.Index(line, "(")
 	if idx != -1 {
-		require.True(s.T, strings.HasSuffix(line, "]"))
+		require.True(s.T, strings.HasSuffix(line, ")"))
 		details = parsePartitionStateDetails(line[idx+1 : len(line)-1])
 		line = line[:idx-1]
 	}