diff --git a/image_prediction/stitcher/stitcher.py b/image_prediction/stitcher/stitcher.py
index 605790e..441ea2e 100644
--- a/image_prediction/stitcher/stitcher.py
+++ b/image_prediction/stitcher/stitcher.py
@@ -8,34 +8,43 @@ from image_prediction.stitcher.utils import make_coord_getter, make_group_merger
 from image_prediction.utils.generic import until
 
 
+def group_by_coordinate(pairs, coord_getter):
+    pairs = sorted(pairs, key=coord_getter)
+    return map(compose(list, second), groupby(pairs, coord_getter))
+
+
+class CoordGrouper:
+    def __init__(self, axis):
+
+        self.c1_getter = make_coord_getter(f"{other_axis(axis)}1")
+        self.c2_getter = make_coord_getter(f"{other_axis(axis)}2")
+
+    def get_c1(self, pair: ImageMetadataPair):
+        return self.c1_getter(pair)
+
+    def group_pairs_by_c1(self, pairs):
+        return group_by_coordinate(pairs, self.c1_getter)
+
+    def group_pairs_by_c2(self, pairs):
+        return group_by_coordinate(pairs, self.c2_getter)
+
+
+def other_axis(axis):
+    return "y" if axis == "x" else "x"
+
+
 class Stitcher:
-    @staticmethod
-    def groupby(pairs, coord_getter):
-        pairs = sorted(pairs, key=coord_getter)
-        return map(compose(list, second), groupby(pairs, coord_getter))
-
-    @staticmethod
-    def other_axis(axis):
-        return "y" if axis == "x" else "x"
-
     def merge_along_axis(self, pairs, axis):
-        def group_pairs_by_c1(pairs):
-            return self.groupby(pairs, c1_getter)
-
-        def group_by_c2(pairs):
-            return self.groupby(pairs, c2_getter)
-
         def group_pairs_within_groups_by_c2(groups):
-            return map(group_by_c2, groups)
+            return map(grouper.group_pairs_by_c2, groups)
 
         def merge_groups_along_orthogonal_axis(groups):
             return map(group_merger, groups)
 
-        c1_getter = make_coord_getter(f"{self.other_axis(axis)}1")
-        c2_getter = make_coord_getter(f"{self.other_axis(axis)}2")
+        grouper = CoordGrouper(axis)
         group_merger = make_group_merger(axis)
 
-        groups_of_pairs_with_same_c1 = group_pairs_by_c1(pairs)
+        groups_of_pairs_with_same_c1 = grouper.group_pairs_by_c1(pairs)
         groups_of_groups_of_pairs_with_same_c1_and_c2 = group_pairs_within_groups_by_c2(groups_of_pairs_with_same_c1)
         groups_of_pairs_with_matching_c1_and_c2 = chain(*groups_of_groups_of_pairs_with_same_c1_and_c2)
         groups_of_merged_pairs = merge_groups_along_orthogonal_axis(groups_of_pairs_with_matching_c1_and_c2)