ConfusionMatrix supports file patterns. (#290)

Author: qimingj

google/datalab/ml/_confusion_matrix.py

@@ -59,8 +59,14 @@ def from_csv(input_csv, headers=None, schema_file=None):
       names = [x['name'] for x in schema]
     else:
       raise ValueError('Either headers or schema_file is needed')
-    with _util.open_local_or_gcs(input_csv, mode='r') as f:
-      df = pd.read_csv(f, names=names)
+
+    all_files = _util.glob_files(input_csv)
+    all_df = []
+    for file_name in all_files:
+      with _util.open_local_or_gcs(file_name, mode='r') as f:
+        all_df.append(pd.read_csv(f, names=names))
+    df = pd.concat(all_df, ignore_index=True)
+
     if 'target' not in df or 'predicted' not in df:
       raise ValueError('Cannot find "target" or "predicted" column')