Iterator in BlockDatacontainer (#1558)

* Iterator in BlockDatacontainer bugfix
---------

Co-authored by: Margaret Duff <43645617+MargaretDuff@users.noreply.github.com>
Co-authored by: Vaggelis Papoutsellis <epapoutsellis@gmail.com>

CHANGELOG.md

@@ -1,11 +1,13 @@
 
 * x.x.x
   - Allow reduction methods on the DataContainer class to accept axis argument as string which matches values in dimension_labels
-  - Added the functions `set_norms` and `get_norms` to the `BlockOperator` class
-  - Internal variable name change in BlockOperator to aid understanding
+  - Added the functions `set_norms` and `get_norms` to the `BlockOperator` class 
+  - Internal variable name change in BlockOperator to aid understanding 
+  - Bug fix for BlockDataContainer as iterator
   - Dropped support for IPP versions older than 2021.10 due to header changes
   - Fix build include directories
 
+
 * 23.1.0
   - Fix bug in IndicatorBox proximal_conjugate
   - Allow CCPi Regulariser functions for non CIL object

Wrappers/Python/cil/framework/BlockDataContainer.py

@@ -86,6 +86,7 @@ def __init__(self, *args, **kwargs):
 
     def __iter__(self):
         '''BlockDataContainer is Iterable'''
+        self.index=0
         return self
     def next(self):
         '''python2 backwards compatibility'''

Wrappers/Python/test/test_BlockDataContainer.py

@@ -20,7 +20,7 @@
 import unittest
 from utils import initialise_tests
 import numpy as np
-from cil.framework import ImageGeometry, AcquisitionGeometry
+from cil.framework import ImageGeometry, AcquisitionGeometry, VectorGeometry
 from cil.framework import ImageData, AcquisitionData, Partitioner
 from cil.framework import BlockDataContainer, BlockGeometry
 import functools
@@ -851,6 +851,23 @@ def test_sapyb_ab_blockdc_y_dc(self):
         res = BlockDataContainer(res0, res2)
 
         self.assertBlockDataContainerEqual(out, res)
+
+    def test_iterator(self):
+        ig0 = VectorGeometry(5)
+        data0=ig0.allocate(0)
+        data1=ig0.allocate(1)
+        data2=ig0.allocate(2)
+        container=BlockDataContainer(data0,data1,data2)
+        a=[]
+        for data in container:
+            a.append(list(data.array))
+        self.assertListEqual(a, [[0.,0.,0.,0.,0.],[1.,1.,1.,1.,1.],[2,2,2,2,2]])
+
+        a=[] #check it works a second time! 
+        for data in container:
+            a.append(list(data.array))
+        self.assertListEqual(a, [[0.,0.,0.,0.,0.],[1.,1.,1.,1.,1.],[2,2,2,2,2]])
+
 
 class TestBlockGeometry(unittest.TestCase):
     def setUp(self):
@@ -920,7 +937,8 @@ def test_partition_diff_num_batches(self):
         with self.assertRaises(ValueError):
             data = self.data.partition(num_batches, 'sequential')
 
-
+
+
 
 
 
@@ -941,4 +959,6 @@ def assertDataIsTheSame(self, data, idxs, msg=None):
                     wrong += 1
                 k += 1
 
-        assert wrong == 0
+        assert wrong == 0
+
+