Append a merge filter to pipelines that consist of readers only

Author: gsakkis

pdal/pipeline.py

@@ -102,7 +102,10 @@ def get_meshio(self, idx: int) -> Optional[Mesh]:
     def _get_json(self) -> str:
         options_list = []
         stage2tag: Dict[Stage, str] = {}
-        for stage in self._stages:
+        stages = self._stages
+        if all(isinstance(stage, Reader) for stage in stages):
+            stages = [*stages, Filter.merge()]
+        for stage in stages:
             stage2tag[stage] = stage.tag or _generate_tag(stage, stage2tag.values())
             options = stage.options
             options["tag"] = stage2tag[stage]

test/test_pipeline.py

@@ -249,6 +249,20 @@ def test_logging(self, filename):
         assert "\nexiting filter()\n" in r.log
         assert "(pypipeline writers.las Debug)" in r.log
 
+    def test_only_readers(self):
+        """Does a pipeline that consists of only readers return the merged data"""
+        read = pdal.Reader("test/data/*.las")
+        r1 = read.pipeline()
+        count1 = r1.execute()
+        array1 = r1.arrays[0]
+
+        r2 = read | read
+        count2 = r2.execute()
+        array2 = r2.arrays[0]
+
+        assert count2 == 2 * count1
+        np.testing.assert_array_equal(np.concatenate([array1, array1]), array2)
+
 
 class TestArrayLoad:
     def test_merged_arrays(self):