Update app.py

app.py

@@ -81,13 +81,23 @@ def predict_linear(strain, dose, soil_n, soil_p, soil_k, ph,
 # -----------------------------
 # 4️⃣ Gradio Interface
 # -----------------------------
+invalid_strains = ["Strains", "strain1", "strain2", ""]
+valid_strain = next(
+    (s for s in strain_names if pd.notna(s) and s not in invalid_strains), 
+    strain_names[0]  # fallback if none found
+)
+
 with gr.Blocks(title="Linear Regression Plant Predictor") as demo:
     gr.Markdown("<h1 style='text-align:center'>Linear Regression — Plant Yield Predictor</h1>")
 
     with gr.Row():
         with gr.Column(scale=1):
             gr.Markdown("### Plant & Strain")
-            strain_input = gr.Dropdown(strain_names, label="Select Strain", value=strain_names[0])
+            strain_input = gr.Dropdown(
+                strain_names,
+                label="Select Strain",
+                value=valid_strain  # first valid, non-NaN, non-invalid strain
+            )
             row_selector = gr.Dropdown(row_options, label="Select Row", value="None, Enter Manually")
 
             gr.Markdown("### Input Parameters")