Dev/rosenblatttransform (#241)

- added rosenblatttransform 
- added 3x3 eta methods 
- interpolation can be used with various eta functions
- added documentation for interpolation, eta calculation 
- exposed full eta struct in python 
- disable ClusterFinder for 2x2 clusters 
- factory function for ClusterVector

---------

Co-authored-by: Dhanya Thattil <dhanya.thattil@psi.ch>
Co-authored-by: Erik Fröjdh <erik.frojdh@psi.ch>

python/tests/test_ClusterVector.py

@@ -5,7 +5,7 @@ import time
 from pathlib import Path
 import pickle
 
-from aare import ClusterFile, ClusterVector
+from aare import ClusterFile, ClusterVector, calculate_eta2
 from aare import _aare
 from conftest import test_data_path
 
@@ -44,6 +44,19 @@ def test_max_2x2_sum():
     assert max_2x2[0]["index"] == 2
 
 
+def test_eta2(): 
+    """calculate eta2"""
+    cv = _aare.ClusterVector_Cluster3x3i()
+    cv.push_back(_aare.Cluster3x3i(19, 22, np.ones(9, dtype=np.int32)))
+    assert cv.size == 1
+    eta2 = calculate_eta2(cv)
+    assert eta2.size == 1
+    assert eta2[0]["x"] == 0.5
+    assert eta2[0]["y"] == 0.5
+    assert eta2[0]["c"] == 0
+    assert eta2[0]["sum"] == 4
+
+
 def test_make_a_hitmap_from_cluster_vector():
     cv = _aare.ClusterVector_Cluster3x3i()
 
@@ -74,11 +87,11 @@ def test_2x2_reduction():
     reduced_cv = np.array(_aare.reduce_to_2x2(cv), copy=False) 
 
     assert reduced_cv.size == 2
-    assert reduced_cv[0]["x"] == 4
+    assert reduced_cv[0]["x"] == 5
     assert reduced_cv[0]["y"] == 5
     assert (reduced_cv[0]["data"] == np.array([[2, 3], [2, 2]], dtype=np.int32)).all()
-    assert reduced_cv[1]["x"] == 4
-    assert reduced_cv[1]["y"] == 6
+    assert reduced_cv[1]["x"] == 5
+    assert reduced_cv[1]["y"] == 5
     assert (reduced_cv[1]["data"] == np.array([[2, 2], [2, 3]], dtype=np.int32)).all()
     
     
@@ -93,6 +106,6 @@ def test_3x3_reduction():
     reduced_cv = np.array(_aare.reduce_to_3x3(cv), copy=False)  
 
     assert reduced_cv.size == 2
-    assert reduced_cv[0]["x"] == 4
+    assert reduced_cv[0]["x"] == 5
     assert reduced_cv[0]["y"] == 5
-    assert (reduced_cv[0]["data"] == np.array([[1.0, 2.0, 1.0], [2.0, 2.0, 3.0], [1.0, 2.0, 1.0]], dtype=np.double)).all()
+    assert (reduced_cv[0]["data"] == np.array([[2.0, 1.0, 1.0], [2.0, 3.0, 1.0], [2.0, 1.0, 1.0]], dtype=np.double)).all()