Fix apply_to_collection(defaultdict)

CHANGELOG.md

@@ -5,6 +5,89 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 
+## [1.6.0] - 2022-MM-DD
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+### Deprecated
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+### Removed
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+### Fixed
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+- Fixed `apply_to_collection(defaultdict)` ([#10316](https://github.com/PyTorchLightning/pytorch-lightning/issues/10316))
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 ## [1.5.0] - 2021-11-02
 
 ### Added
@@ -132,7 +215,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Added support for empty `gpus` list to run on CPU ([#10246](https://github.com/PyTorchLightning/pytorch-lightning/pull/10246))
 - Added a warning if multiple batch sizes are found from ambiguous batch ([#10247](https://github.com/PyTorchLightning/pytorch-lightning/pull/10247))
 
-
 ### Changed
 
 - Trainer now raises a `MisconfigurationException` when its methods are called with `ckpt_path="best"` but a checkpoint callback isn't configured ([#9841](https://github.com/PyTorchLightning/pytorch-lightning/pull/9841))
@@ -184,7 +266,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Enabled `on_load_checkpoint` for `LightningDataModule` for all `trainer_fn` ([#10238](https://github.com/PyTorchLightning/pytorch-lightning/pull/10238))
 - Allowed separate config files for parameters with class type when LightningCLI is in `subclass_mode=False` ([#10286](https://github.com/PyTorchLightning/pytorch-lightning/pull/10286))
 
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 ### Deprecated
 
 - Deprecated Trainer argument `terminate_on_nan` in favor of `detect_anomaly`([#9175](https://github.com/PyTorchLightning/pytorch-lightning/pull/9175))
@@ -220,7 +301,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Deprecated `lr_sch_names` from `LearningRateMonitor` ([#10066](https://github.com/PyTorchLightning/pytorch-lightning/pull/10066))
 - Deprecated `ProgressBar` callback in favor of `TQDMProgressBar` ([#10134](https://github.com/PyTorchLightning/pytorch-lightning/pull/10134))
 
-
 ### Removed
 
 - Removed deprecated `metrics` ([#8586](https://github.com/PyTorchLightning/pytorch-lightning/pull/8586/))
@@ -264,7 +344,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Removed automatic patching of `{train,val,test,predict}_dataloader()` on the `LightningModule` ([#9764](https://github.com/PyTorchLightning/pytorch-lightning/pull/9764))
 - Removed `pytorch_lightning.trainer.connectors.OptimizerConnector` ([#10120](https://github.com/PyTorchLightning/pytorch-lightning/pull/10120))
 
-
 ### Fixed
 
 - Fixed ImageNet evaluation in example ([#10179](https://github.com/PyTorchLightning/pytorch-lightning/pull/10179))
@@ -473,7 +552,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Added private `prevent_trainer_and_dataloaders_deepcopy` context manager on the `LightningModule` ([#8472](https://github.com/PyTorchLightning/pytorch-lightning/pull/8472))
 - Added support for providing callables to the Lightning CLI instead of types ([#8400](https://github.com/PyTorchLightning/pytorch-lightning/pull/8400))
 
-
 ### Changed
 
 - Decoupled device parsing logic from Accelerator connector to Trainer ([#8180](https://github.com/PyTorchLightning/pytorch-lightning/pull/8180))

pytorch_lightning/utilities/apply_func.py

@@ -14,7 +14,7 @@
 import dataclasses
 import operator
 from abc import ABC
-from collections import OrderedDict
+from collections import defaultdict, OrderedDict
 from collections.abc import Mapping, Sequence
 from copy import copy
 from functools import partial
@@ -102,6 +102,8 @@ def apply_to_collection(
             )
             if include_none or v is not None:
                 out.append((k, v))
+        if isinstance(data, defaultdict):
+            return elem_type(data.default_factory, OrderedDict(out))
         return elem_type(OrderedDict(out))
 
     is_namedtuple = _is_namedtuple(data)

tests/utilities/test_apply_func.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 import dataclasses
 import numbers
-from collections import namedtuple, OrderedDict
+from collections import defaultdict, namedtuple, OrderedDict
 from typing import List
 
 import numpy as np
@@ -153,6 +153,11 @@ def __init__(self, initial_dict):
     reduced = apply_to_collection(to_reduce, int, lambda x: str(x))
     assert reduced == _CustomCollection({"a": "1", "b": "2", "c": "3"})
 
+    # defaultdict
+    to_reduce = defaultdict(int, {"a": 1, "b": 2, "c": 3})
+    reduced = apply_to_collection(to_reduce, int, lambda x: str(x))
+    assert reduced == defaultdict(int, {"a": "1", "b": "2", "c": "3"})
+
 
 def test_apply_to_collection_include_none():
     to_reduce = [1, 2, 3.4, 5.6, 7, (8, 9.1, {10: 10})]