fixed an error.

mini-batch-sgd-logistic-regression-wdbc.py

@@ -74,19 +74,19 @@ class LogisticRegression:
         n_samples = self.x.shape[0]
         batch_size = self.batch_size or n_samples
 
+        # number of batches per iteration
+        n_batches = int(np.ceil(n_samples / batch_size))
+
         for epoch in range(1, self.n_iter + 1):
             shuffled_idx = np.random.permutation(n_samples) # random permutation of the indices
-            x_shuffled = self.x[shuffled_idx]
-            y_shuffled = self.y[shuffled_idx]
-
-            # process execution for each mini‑batch
-            for b in range(0, n_samples, batch_size):
+            for b in range(n_batches):
                 start = b * batch_size
-                end   = start + batch_size
+                end   = min(start + batch_size, n_samples)
                 idx = shuffled_idx[start:end]
 
-                x_batch = x_shuffled[idx]
-                y_batch = y_shuffled[idx]
+                x_batch = self.x[idx]
+                y_batch = self.y[idx]
+
 
                 z = x_batch.dot(self.w)
                 p = self.sigmoid(z)