Support subword and word language models

Closes #199 (closed)

Ref https://redmine.teklia.com/issues/4941

dan/datasets/analyze/statistics.py

 # -*- coding: utf-8 -*-
 import logging
 from collections import Counter, defaultdict
+from functools import partial
 from pathlib import Path
 from typing import Dict, List, Optional
 
@@ -32,23 +33,32 @@ def create_table(
     operations = []
 
     if count:
-        operations.append(("Count", len))
+        operations.append(("Count", len, None))
 
     operations.extend(
         [
-            ("Min", np.min),
-            ("Max", np.max),
-            ("Mean", np.mean),
-            ("Median", np.median),
+            ("Min", np.min, None),
+            ("Max", np.max, None),
+            ("Mean", np.mean, 2),
+            ("Median", np.median, 2),
         ]
     )
     if total:
-        operations.append(("Total", np.sum))
+        operations.append(("Total", np.sum, None))
 
     statistics.add_rows(
         [
-            [col_name, *list(map(operator, data.values()))]
-            for col_name, operator in operations
+            [
+                col_name,
+                *list(
+                    map(
+                        # Round values if needed
+                        partial(round, ndigits=digits),
+                        map(operator, data.values()),
+                    )
+                ),
+            ]
+            for col_name, operator, digits in operations
         ]
     )