Merge pull request #2544 from plotly/fix-hover-labels

fixed bug in hover data

Author: nicolaskruchten

Diff for: CHANGELOG.md

@@ -7,6 +7,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Fixed special cases with `px.sunburst` and `px.treemap` with `path` input ([#2524](https://github.com/plotly/plotly.py/pull/2524))
+- Fixed bug in `hover_data` argument of `px` functions, when the column name is changed with labels and `hover_data` is a dictionary setting up a specific format for the hover data ([#2544](https://github.com/plotly/plotly.py/pull/2544)).
 
 ## [4.8.1] - 2020-05-28
 

Diff for: packages/python/plotly/plotly/express/_core.py

@@ -116,6 +116,18 @@ def get_label(args, column):
         return column
 
 
+def invert_label(args, column):
+    """Invert mapping.
+    Find key corresponding to value column in dict args["labels"].
+    Returns `column` if the value does not exist.
+    """
+    reversed_labels = {value: key for (key, value) in args["labels"].items()}
+    try:
+        return reversed_labels[column]
+    except Exception:
+        return column
+
+
 def _is_continuous(df, col_name):
     return df[col_name].dtype.kind in "ifc"
 
@@ -434,11 +446,13 @@ def make_trace_kwargs(args, trace_spec, trace_data, mapping_labels, sizeref):
         mapping_labels_copy = OrderedDict(mapping_labels)
         if args["hover_data"] and isinstance(args["hover_data"], dict):
             for k, v in mapping_labels.items():
-                if k in args["hover_data"]:
-                    if args["hover_data"][k][0]:
-                        if isinstance(args["hover_data"][k][0], str):
+                # We need to invert the mapping here
+                k_args = invert_label(args, k)
+                if k_args in args["hover_data"]:
+                    if args["hover_data"][k_args][0]:
+                        if isinstance(args["hover_data"][k_args][0], str):
                             mapping_labels_copy[k] = v.replace(
-                                "}", "%s}" % args["hover_data"][k][0]
+                                "}", "%s}" % args["hover_data"][k_args][0]
                             )
                     else:
                         _ = mapping_labels_copy.pop(k)

Diff for: packages/python/plotly/plotly/tests/test_core/test_px/test_px_hover.py

@@ -72,6 +72,18 @@ def test_newdatain_hover_data():
         )
 
 
+def test_formatted_hover_and_labels():
+    df = px.data.tips()
+    fig = px.scatter(
+        df,
+        x="tip",
+        y="total_bill",
+        hover_data={"total_bill": ":.1f"},
+        labels={"total_bill": "Total bill"},
+    )
+    assert ":.1f" in fig.data[0].hovertemplate
+
+
 def test_fail_wrong_column():
     with pytest.raises(ValueError) as err_msg:
         px.scatter(