clean up node naming

backend/nodes/statistics.py

@@ -0,0 +1,44 @@
+from __future__ import annotations
+import numpy as np
+from backend.node_registry import register_node
+from backend.data_types import DataField, RecordTable
+
+
+@register_node(display_name="Statistics")
+class Statistics:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+            }
+        }
+
+    OUTPUTS = (
+        ('RECORD_TABLE', 'stats'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Compute basic surface statistics: min, max, mean, RMS roughness, median, "
+        "and skewness. Equivalent to gwy_data_field_get_min/max/avg/rms."
+    )
+
+    def process(self, field: DataField) -> tuple:
+        d = field.data
+        mean = float(d.mean())
+        rms = float(np.sqrt(np.mean((d - mean) ** 2)))
+        skewness = float(np.mean(((d - mean) / rms) ** 3)) if rms > 0 else 0.0
+        kurtosis = float(np.mean(((d - mean) / rms) ** 4)) if rms > 0 else 0.0
+
+        table = RecordTable([
+            {"quantity": "min",      "value": float(d.min()),    "unit": field.si_unit_z},
+            {"quantity": "max",      "value": float(d.max()),    "unit": field.si_unit_z},
+            {"quantity": "mean",     "value": mean,              "unit": field.si_unit_z},
+            {"quantity": "RMS",      "value": rms,               "unit": field.si_unit_z},
+            {"quantity": "median",   "value": float(np.median(d)), "unit": field.si_unit_z},
+            {"quantity": "skewness", "value": skewness,          "unit": ""},
+            {"quantity": "kurtosis", "value": kurtosis,          "unit": ""},
+            {"quantity": "range",    "value": float(d.max() - d.min()), "unit": field.si_unit_z},
+        ])
+        return (table,)