refactoring

test/unit_tests/image_stitcher_test.py

@@ -1,5 +1,5 @@
 from copy import deepcopy
-from functools import partial
+from functools import partial, reduce
 from itertools import groupby
 from itertools import starmap, chain, repeat
 from typing import Iterable, List
@@ -128,16 +128,18 @@ class Stitcher:
 
 def merge_group(group):
 
-    def merge_with(current_pair, pairs):
+    def merge_with(aggregation_pair, pairs):
 
-        to_remove = []
+        def aggregate_on_head(pairs_aggr: Iterable[ImageMetadataPair], pair: ImageMetadataPair):
+            """Keeps the image that is being merged with as the head and aggregates non-mergables in the tail"""
+            aggr, non_aggr = juxt(first, rest)(pairs_aggr)
+            if y2_getter(aggr) == y1_getter(pair):
+                aggr = merge_pair_vertically(aggr, pair)
+                return aggr, *non_aggr
+            else:
+                return aggr, pair, *non_aggr
 
-        for pair in pairs:
-            if y2_getter(current_pair) == y1_getter(pair):
-                current_pair = merge_pair_vertically(current_pair, pair)
-                to_remove.append(pair)
-
-        return [current_pair, *filter(lambda p: p not in to_remove, pairs)]
+        return list(reduce(aggregate_on_head, pairs, [aggregation_pair]))
 
     pairs = list(group)