Added operator to format a data type to a python list string

src/Bonsai.ML.HiddenMarkovModels/FormatToPythonList.cs

@@ -0,0 +1,98 @@
+using System.Collections;
+using System.Linq;
+using System.Text;
+using System.ComponentModel;
+using System.Reactive.Linq;
+using System;
+
+namespace Bonsai.ML.HiddenMarkovModels
+{
+    /// <summary>
+    /// Represents an operator that can convert an object into a properly formatted string that is consistent with a python list.
+    /// For example, a tuple (1, 2, 3) will be converted to the string "[1, 2, 3]".
+    /// </summary>
+    [Combinator]
+    [Description("Converts an object into a properly formatted string that is consistent with a python list.")]
+    [WorkflowElementCategory(ElementCategory.Transform)]
+    public class FormatToPythonList
+    {
+        /// <summary>
+        /// Transforms the elements of an observable sequence into a properly formatted string that is consistent with a python list.
+        /// </summary>
+        public IObservable<string> Process<TSource>(IObservable<TSource> source)
+        {
+            return source.Select(value => PythonListHelper.ConvertToPythonListString(value));
+        }
+    }
+
+    internal static class PythonListHelper
+    {
+        public static string ConvertToPythonListString(object obj)
+        {
+            return $"[{ConvertToCommaSeparatedString(obj)}]";
+        }
+
+        public static string ConvertToCommaSeparatedString(object obj)
+        {
+            if (obj == null) return "None";
+
+            if (obj is string)
+            {
+                return obj.ToString();
+            }
+
+            if (obj is IEnumerable enumerable)
+            {
+                var sb = new StringBuilder();
+                foreach (var item in enumerable)
+                {
+                    if (sb.Length > 0)
+                    {
+                        sb.Append(", ");
+                    }
+                    sb.Append(ConvertToCommaSeparatedString(item));
+                }
+                return sb.ToString();
+            }
+
+            var tupleType = obj.GetType();
+            if (tupleType.IsGenericType && tupleType.FullName.StartsWith("System.Tuple"))
+            {
+                var values = tupleType.GetProperties()
+                                    .Where(p => p.Name.StartsWith("Item"))
+                                    .Select(p => p.GetValue(obj));
+
+                var sb = new StringBuilder();
+                foreach (var value in values)
+                {
+                    if (sb.Length > 0)
+                    {
+                        sb.Append(", ");
+                    }
+                    sb.Append(ConvertToCommaSeparatedString(value));
+                }
+                return sb.ToString();
+            }
+
+            if (tupleType.IsValueType && tupleType.FullName.StartsWith("System.ValueTuple"))
+            {
+                var fields = tupleType.GetFields()
+                                    .Where(f => f.Name.StartsWith("Item"))
+                                    .Select(f => f.GetValue(obj));
+
+                var sb = new StringBuilder();
+                foreach (var field in fields)
+                {
+                    if (sb.Length > 0)
+                    {
+                        sb.Append(", ");
+                    }
+                    sb.Append(ConvertToCommaSeparatedString(field));
+                }
+                return sb.ToString();
+            }
+
+            return obj.ToString();
+        }
+    }
+}