Updated metrics serialization (#3095)

* Added _tree_map and _tree_apply2 to simplify checkpoint/metric code

* Fixed Metric tests

* Added state_dict support for MetricsLambda and contrib metrics

* Few other fixes

* Test fix

* More fixes in Metrics for distributed mode

Author: vfdev-5

ignite/contrib/metrics/regression/canberra_metric.py

@@ -63,6 +63,7 @@ class CanberraMetric(_BaseRegression):
         - Fixed implementation: ``abs`` in denominator.
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors",)
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/fractional_absolute_error.py

@@ -58,6 +58,7 @@ class FractionalAbsoluteError(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors", "_num_examples")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/fractional_bias.py

@@ -58,6 +58,7 @@ class FractionalBias(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors", "_num_examples")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/geometric_mean_absolute_error.py

@@ -58,6 +58,7 @@ class GeometricMeanAbsoluteError(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors", "_num_examples")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/geometric_mean_relative_absolute_error.py

@@ -69,6 +69,7 @@ class GeometricMeanRelativeAbsoluteError(_BaseRegression):
 
             0.0...
     """
+    _state_dict_all_req_keys = ("_predictions", "_targets")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/manhattan_distance.py

@@ -59,6 +59,7 @@ class ManhattanDistance(_BaseRegression):
         - Fixed sklearn compatibility.
         - Workes with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors",)
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/maximum_absolute_error.py

@@ -58,6 +58,7 @@ class MaximumAbsoluteError(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_max_of_absolute_errors",)
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/mean_absolute_relative_error.py

@@ -58,6 +58,7 @@ class MeanAbsoluteRelativeError(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_absolute_relative_errors", "_num_samples")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/mean_error.py

@@ -55,6 +55,7 @@ class MeanError(_BaseRegression):
 
             0.625...
     """
+    _state_dict_all_req_keys = ("_sum_of_errors", "_num_examples")
 
     @reinit__is_reduced
     def reset(self) -> None:

ignite/contrib/metrics/regression/mean_normalized_bias.py

@@ -58,6 +58,7 @@ class MeanNormalizedBias(_BaseRegression):
     .. versionchanged:: 0.4.5
         - Works with DDP.
     """
+    _state_dict_all_req_keys = ("_sum_of_errors", "_num_examples")
 
     @reinit__is_reduced
     def reset(self) -> None: