Merge pull request #4011 from m-ad/fix-datetime-trendline

Fix trendlines for datetimes (#3683)

Author: nicolaskruchten

CHANGELOG.md

@@ -13,7 +13,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
       this feature was anonymously sponsored: thank you to our sponsor!
     - Add `marker.cornerradius` attribute to `treemap` trace [[#6351](https://github.com/plotly/plotly.js/pull/6351)]
 ### Fixed
-  - Fixed the usage of sume deprecated NumPy types which were removed in NumPy 1.24 [[#3997](https://github.com/plotly/plotly.py/pull/3997)]
+  - Fixed the usage of some deprecated NumPy types which were removed in NumPy 1.24 [[#3997](https://github.com/plotly/plotly.py/pull/3997)]
+  - Fixed bug for trendlines with datetime axes [[#3683](https://github.com/plotly/plotly.py/issues/3683)]
 
 ## [5.11.0] - 2022-10-27
 

packages/python/plotly/plotly/express/_core.py

@@ -328,7 +328,7 @@ def make_trace_kwargs(args, trace_spec, trace_data, mapping_labels, sizeref):
                     x = sorted_trace_data[args["x"]].values
 
                     if x.dtype.type == np.datetime64:
-                        x = x.astype(int) / 10**9  # convert to unix epoch seconds
+                        x = x.astype(np.int64) / 10**9  # convert to unix epoch seconds
                     elif x.dtype.type == np.object_:
                         try:
                             x = x.astype(np.float64)