Format the index too (#198)

Author: mwouts

docs/pandas_style.md

@@ -59,7 +59,7 @@ s.background_gradient(axis=None, cmap="YlOrRd")
 We can also choose how the data is formatted:
 
 ```{code-cell}
-s.format("{:.3f}")
+s.format("{:.3f}").format_index("{:.3f}")
 ```
 
 ## Caption

itables/sample_dfs.py

@@ -390,6 +390,11 @@ def get_pandas_styler():
     s = df.style
     s.background_gradient(axis=None, cmap="YlOrRd")
     s.format("{:.3f}")
+    try:
+        s.format_index("{:.3f}")
+    except AttributeError:
+        # Python 3.7 AttributeError: 'Styler' object has no attribute 'format_index'
+        pass
 
     s.set_caption(
         "A Pandas Styler object with background colors and tooltips"

tests/test_documentation_notebooks_run.py

@@ -11,7 +11,7 @@
 except ImportError:
     pl = None
 
-pytestmark = pytest.mark.skipif(sys.version_info < (3, 7), reason="Require Python>=3.7")
+pytestmark = pytest.mark.skipif(sys.version_info < (3, 8), reason="Require Python>=3.8")
 
 
 def list_doc_notebooks():