Fixed a bug in display that experiment id gets dropped when it's 0.

PiperOrigin-RevId: 771193952

Author: tcya

confidence_interval_display.py

@@ -442,7 +442,7 @@ def dimension_formatter(x,
   d = []
   if description:
     d.append(span(description, 'ci-display-description-text'))
-  if expr_id:
+  if expr_id is not None:
     d.append(span(expr_id, 'ci-display-experiment-id'))
   if slice_info:
     d.append(span(slice_info, 'ci-display-dimension'))

operations_test.py

@@ -1355,21 +1355,21 @@ def test_display_change(self):
     df = pd.DataFrame({
         'x': [1, 100, 2, 100, 3, 100],
         'cookie': [1, 2, 3, 1, 2, 3],
-        'grp': ['A', 'B'] * 3,
+        'grp': [1, 0] * 3,
     })
-    change = metrics.Sum('x') | operations.PercentChange('grp', 'A')
+    change = metrics.Sum('x') | operations.PercentChange('grp', 1)
     m = operations.Jackknife('cookie', change, 0.9)
     res = m.compute_on(df)
     output = res.display(return_formatted_df=True)
     expected = pd.DataFrame(
         {
             'Dimensions': [
                 (
-                    '<div><div><span class="ci-display-experiment-id">A</span>'
+                    '<div><div><span class="ci-display-experiment-id">1</span>'
                     '</div></div>'
                 ),
                 (
-                    '<div><div><span class="ci-display-experiment-id">B</span>'
+                    '<div><div><span class="ci-display-experiment-id">0</span>'
                     '</div></div>'
                 ),
             ],