copy anndata in metric decorator (openproblems-bio#819)

Author: scottgigante-immunai

CONTRIBUTING.md

@@ -178,6 +178,9 @@ Metrics should take an AnnData object and return a `float`.
 function metric(AnnData adata) -> float
 ```
 
+Note that the AnnData object is passed to the metric function as a copy, so there is no
+need to copy it internally, even if you modify the object.
+
 Task-specific APIs are described in the README for each task.
 
 * [Label Projection](openproblems/tasks/label_projection)

openproblems/tools/decorators.py

@@ -126,9 +126,9 @@ def metric(metric_name, maximize, paper_reference, image="openproblems"):
 
     def decorator(func):
         @functools.wraps(func)
-        def apply_metric(*args, **kwargs):
+        def apply_metric(adata: anndata.AnnData, *args, **kwargs):
             log.debug("Running {} metric".format(func.__name__))
-            return func(*args, **kwargs)
+            return func(adata.copy(), *args, **kwargs)
 
         apply_metric.metadata = dict(
             metric_name=metric_name,