Sort numeric text columns by value in the cluster tables

docs/changelog.md

@@ -50,6 +50,9 @@ behavior they verify rather than listed separately.
   Escape, and outside clicks release filter focus so global shortcuts resume.
 - Display metadata columns containing multiple values in the Cluster and
   Similarity Views instead of leaving their cells blank.
+- Sort text columns holding numbers, such as the channel column `ch`, by
+  numeric value in the Cluster and Similarity Views. Channel 2 no longer
+  appears after channel 10.
 
 ### Changed
 

phy/gui/tests/test_widgets.py

@@ -566,6 +566,36 @@ def test_table_change_and_sort_2(qtbot, table):
     _assert(table.get_ids, [9, 8, 7, 6, 4, 3, 2, 1, 0, 5])
 
 
+def test_table_sort_numeric_strings(qtbot):
+    # The `ch` column of the cluster view holds channel labels, which are strings.
+    # A plain string comparison sorts '10' before '2', so numeric strings have to be
+    # compared as numbers.
+    data = [{'id': i, 'ch': ch} for i, ch in enumerate(['2', '10', '1', '21', '3'])]
+    table = Table(columns=['id', 'ch'], value_names=['id', 'ch'], data=data)
+    _wait_until_table_ready(qtbot, table)
+
+    table.sort_by('ch', 'asc')
+    _assert(table.get_ids, [2, 0, 4, 1, 3])
+
+    table.sort_by('ch', 'desc')
+    _assert(table.get_ids, [3, 1, 4, 0, 2])
+
+    table.close()
+
+
+def test_table_sort_mixed_strings(qtbot):
+    # In a column that mixes numbers and free text, the numbers come first in numeric
+    # order and the remaining entries keep their string ordering.
+    data = [{'id': i, 'label': label} for i, label in enumerate(['mua', '10', 'good', '2'])]
+    table = Table(columns=['id', 'label'], value_names=['id', 'label'], data=data)
+    _wait_until_table_ready(qtbot, table)
+
+    table.sort_by('label', 'asc')
+    _assert(table.get_ids, [3, 1, 2, 0])
+
+    table.close()
+
+
 def test_table_change_metadata_preserves_sort(qtbot):
     data = [
         {'id': 0, 'count': 30, 'group': 'noise'},

phy/gui/widgets.py

@@ -9,6 +9,7 @@
 import inspect
 import json
 import logging
+import math
 import re
 import sys
 from contextlib import contextmanager
@@ -330,6 +331,25 @@ def predicate(row):
     return predicate, True
 
 
+def _text_sort_key(value):
+    """Return a sort key that orders numeric text by value rather than character by character.
+
+    Columns such as `ch` hold channel labels, which are strings, so a plain string
+    comparison places '10' before '2'. Numeric entries sort first, in numeric order, and
+    the remaining entries keep their string ordering.
+
+    """
+    text = value if isinstance(value, str) else str(value)
+    try:
+        number = float(text)
+    except ValueError:
+        return (1, 0.0, text)
+    # NaN has no consistent ordering, so keep it with the non-numeric entries.
+    if math.isnan(number):
+        return (1, 0.0, text)
+    return (0, number, '')
+
+
 class _TableModel(QAbstractTableModel):
     """Model backing the native Qt table."""
 
@@ -438,6 +458,8 @@ def lessThan(self, left, right):
             return False
         if right_value is None:
             return True
+        if isinstance(left_value, str) or isinstance(right_value, str):
+            return _text_sort_key(left_value) < _text_sort_key(right_value)
         try:
             return bool(left_value < right_value)
         except TypeError: