Fix mypy errors attributed to `pytorch_lightning.loggers.csv_logs.py` (#13538)

Co-authored-by: Akihiro Nitta <nitta@akihironitta.com>

pyproject.toml

@@ -61,7 +61,6 @@ module = [
     "pytorch_lightning.distributed.dist",
     "pytorch_lightning.loggers.base",
     "pytorch_lightning.loggers.comet",
-    "pytorch_lightning.loggers.csv_logs",
     "pytorch_lightning.loggers.mlflow",
     "pytorch_lightning.loggers.neptune",
     "pytorch_lightning.loggers.tensorboard",

src/pytorch_lightning/loggers/csv_logs.py

@@ -22,7 +22,7 @@ import csv
 import logging
 import os
 from argparse import Namespace
-from typing import Any, Dict, Optional, Union
+from typing import Any, Dict, List, Optional, Union
 
 from torch import Tensor
 
@@ -49,8 +49,8 @@ class ExperimentWriter:
     NAME_METRICS_FILE = "metrics.csv"
 
     def __init__(self, log_dir: str) -> None:
-        self.hparams = {}
-        self.metrics = []
+        self.hparams: Dict[str, Any] = {}
+        self.metrics: List[Dict[str, float]] = []
 
         self.log_dir = log_dir
         if os.path.exists(self.log_dir) and os.listdir(self.log_dir):
@@ -69,7 +69,7 @@ class ExperimentWriter:
     def log_metrics(self, metrics_dict: Dict[str, float], step: Optional[int] = None) -> None:
         """Record metrics."""
 
-        def _handle_value(value):
+        def _handle_value(value: Union[Tensor, Any]) -> Any:
             if isinstance(value, Tensor):
                 return value.item()
             return value
@@ -126,7 +126,7 @@ class CSVLogger(Logger):
     def __init__(
         self,
         save_dir: str,
-        name: Optional[str] = "lightning_logs",
+        name: str = "lightning_logs",
         version: Optional[Union[int, str]] = None,
         prefix: str = "",
         flush_logs_every_n_steps: int = 100,
@@ -136,7 +136,7 @@ class CSVLogger(Logger):
         self._name = name or ""
         self._version = version
         self._prefix = prefix
-        self._experiment = None
+        self._experiment: Optional[ExperimentWriter] = None
         self._flush_logs_every_n_steps = flush_logs_every_n_steps
 
     @property
@@ -161,7 +161,7 @@ class CSVLogger(Logger):
         return log_dir
 
     @property
-    def save_dir(self) -> Optional[str]:
+    def save_dir(self) -> str:
         """The current directory where logs are saved.
 
         Returns:
@@ -169,7 +169,7 @@ class CSVLogger(Logger):
         """
         return self._save_dir
 
-    @property
+    @property  # type: ignore[misc]
     @rank_zero_experiment
     def experiment(self) -> ExperimentWriter:
         r"""
@@ -182,7 +182,7 @@ class CSVLogger(Logger):
             self.logger.experiment.some_experiment_writer_function()
 
         """
-        if self._experiment:
+        if self._experiment is not None:
             return self._experiment
 
         os.makedirs(self.root_dir, exist_ok=True)
@@ -220,7 +220,7 @@ class CSVLogger(Logger):
         return self._name
 
     @property
-    def version(self) -> int:
+    def version(self) -> Union[int, str]:
         """Gets the version of the experiment.
 
         Returns:
@@ -230,7 +230,7 @@ class CSVLogger(Logger):
             self._version = self._get_next_version()
         return self._version
 
-    def _get_next_version(self):
+    def _get_next_version(self) -> int:
         root_dir = self.root_dir
 
         if not os.path.isdir(root_dir):