Bugfix: prevent Excel from turning your 4e2 into 4.00E+02

app.py

@@ -4,6 +4,7 @@ import numpy as np
 from sklearn.preprocessing import PolynomialFeatures
 import statsmodels.api as sm
 import scipy.optimize as opt
+import csv
 
 # Global state
 data_df     = None
@@ -70,7 +71,10 @@ def export_csv():
     if data_df is None:
         return gr.update(visible=False, value=None)
     path = "training_data.csv"
-    data_df.to_csv(path, index=False)
+    # wrap every field in double-quotes so Excel won’t re-interpret it
+    data_df.to_csv(path, index=False,
+                  quoting=csv.QUOTE_ALL,
+                  escapechar='\\')
     return gr.update(visible=True, value=path)
 
 # Panel 2: Train Hierarchical Quadratic RSM