Fixed encoding issues on terminals that do not support unicode characters

CHANGELOG.md

@@ -135,6 +135,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - When using custom DataLoaders in LightningDataModule, multiple inheritance is resolved properly ([#12716](https://github.com/PyTorchLightning/pytorch-lightning/pull/12716))
 
 
+- Fixed encoding issues on terminals that do not support unicode characters ([#12828](https://github.com/PyTorchLightning/pytorch-lightning/pull/12828))
+
+
 - Fixed support for `ModelCheckpoint` monitors with dots ([#12783](https://github.com/PyTorchLightning/pytorch-lightning/pull/12783))
 
 

pytorch_lightning/loops/dataloader/evaluation_loop.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 import os
 import shutil
+import sys
 from collections import ChainMap, OrderedDict
 from functools import partial
 from typing import Any, IO, Iterable, List, Optional, Sequence, Type, Union
@@ -336,6 +337,10 @@ def _find_value(data: dict, target: str) -> Iterable[Any]:
 
     @staticmethod
     def _print_results(results: List[_OUT_DICT], stage: str, file: Optional[IO[str]] = None) -> None:
+        # print to stdout by default
+        if file is None:
+            file = sys.stdout
+
         # remove the dl idx suffix
         results = [{k.split("/dataloader_idx_")[0]: v for k, v in result.items()} for result in results]
         metrics = sorted({k for keys in apply_to_collection(results, dict, EvaluationLoop._get_keys) for k in keys})
@@ -384,7 +389,16 @@ def _print_results(results: List[_OUT_DICT], stage: str, file: Optional[IO[str]]
                 row_format = f"{{:^{max_length}}}" * len(table_headers)
                 half_term_size = int(term_size / 2)
 
-                bar = "─" * term_size
+                try:
+                    # some terminals do not support this character
+                    if hasattr(file, "encoding") and file.encoding is not None:
+                        "─".encode(file.encoding)
+                except UnicodeEncodeError:
+                    bar_character = "-"
+                else:
+                    bar_character = "─"
+                bar = bar_character * term_size
+
                 lines = [bar, row_format.format(*table_headers).rstrip(), bar]
                 for metric, row in zip(metrics, table_rows):
                     # deal with column overflow

tests/trainer/logging_/test_eval_loop_logging.py

@@ -870,6 +870,23 @@ def test_native_print_results(monkeypatch, inputs, expected):
     assert out.getvalue().replace(os.linesep, "\n") == expected.lstrip()
 
 
+@pytest.mark.parametrize("encoding", ["latin-1", "utf-8"])
+def test_native_print_results_encodings(monkeypatch, encoding):
+    import pytorch_lightning.loops.dataloader.evaluation_loop as imports
+
+    monkeypatch.setattr(imports, "_RICH_AVAILABLE", False)
+
+    out = mock.Mock()
+    out.encoding = encoding
+    EvaluationLoop._print_results(*inputs0, file=out)
+
+    # Attempt to encode everything the file is told to write with the given encoding
+    for call_ in out.method_calls:
+        name, args, kwargs = call_
+        if name == "write":
+            args[0].encode(encoding)
+
+
 expected0 = """
 ┏━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━┓
 ┃       Test metric       ┃      DataLoader 0       ┃       DataLoader 1       ┃