Support multiclass models in the generate_sheet.py script (#896)

Fixes #822

scripts/generate_sheet.py

@@ -5,6 +5,8 @@ import csv
 import os
 from datetime import datetime, timedelta
 
+import numpy as np
+
 from bugbug import bugzilla
 from bugbug.models import get_model_class
 
@@ -31,10 +33,17 @@ def generate_sheet(model_name, token, days, threshold):
 
     for bug in bugs.values():
         p = model.classify(bug, probabilities=True)
+        probability = p[0]
+        if len(probability) > 2:
+            index = np.argmax(probability)
+            prediction = model.class_names[index]
+        else:
+            prediction = "y" if probability[1] >= threshold else "n"
+
         rows.append(
             [
                 f'https://bugzilla.mozilla.org/show_bug.cgi?id={bug["id"]}',
-                "y" if p[0][1] >= threshold else "n",
+                prediction,
                 "",
                 bug["summary"],
             ]