Add DataHandling.add_arrays

This adds a function for lazy people who want to write

```python
dh = create_data_handling((20, 30))
dh.add_arrays('x, y(9), z')
```

instead of

```python
dh = create_data_handling((20, 30))
dh.add_array('x')
dh.add_array('y', values_per_cell=9)
dh.add_array('z')
```

because in most cases you want to use more than one array.

pystencils/datahandling/datahandling_interface.py

@@ -62,6 +62,26 @@ class DataHandling(ABC):
             pystencils field, that can be used to formulate symbolic kernels
         """
 
+    def add_arrays(self, description: str):
+        """Adds multiple arrays using a string description similar to :func:`pystencils.fields`
+
+
+        >>> from pystencils.datahandling import create_data_handling
+        >>> dh = create_data_handling((20, 30))
+        >>> dh.add_arrays('x, y(9)')
+        >>> print(dh.fields)
+        {'x': x: double[20,30], 'y': y(9): double[20,30]}
+        >>> assert dh.fields['x'].shape = (20, 30)
+        >>> assert dh.fields['y'].index_shape = (9,)
+
+        Args:
+            description (str): String description of the fields to add
+        """
+        from pystencils.field import _parse_part1
+
+        for name, indices in _parse_part1(description):
+            self.add_array(name, values_per_cell=indices)
+
     @abstractmethod
     def has_data(self, name):
         """Returns true if a field or custom data element with this name was added."""

pystencils/field.py

@@ -1058,15 +1058,17 @@ type_description_regex = re.compile(r"""
 """, re.VERBOSE | re.IGNORECASE)
 
 
-def _parse_description(description):
-    def parse_part1(d):
+def _parse_part1(d):
+    result = field_description_regex.match(d)
+    while result:
+        name, index_str = result.group(1), result.group(2)
+        index = tuple(int(e) for e in index_str.split(",")) if index_str else ()
+        yield name, index
+        d = d[result.end():]
         result = field_description_regex.match(d)
-        while result:
-            name, index_str = result.group(1), result.group(2)
-            index = tuple(int(e) for e in index_str.split(",")) if index_str else ()
-            yield name, index
-            d = d[result.end():]
-            result = field_description_regex.match(d)
+
+
+def _parse_description(description):
 
     def parse_part2(d):
         result = type_description_regex.match(d)
@@ -1091,7 +1093,7 @@ def _parse_description(description):
     else:
         field_description, field_info = description, 'float64[2D]'
 
-    fields_info = [e for e in parse_part1(field_description)]
+    fields_info = [e for e in _parse_part1(field_description)]
     if not field_info:
         raise ValueError("Could not parse field description")
 

pystencils_tests/test_datahandling.py

@@ -13,7 +13,6 @@ except ImportError:
     pytest = unittest.mock.MagicMock()
 
 
-
 def basic_iteration(dh):
     dh.add_array('basic_iter_test_gl_default')
     dh.add_array('basic_iter_test_gl_3', ghost_layers=3)
@@ -227,3 +226,16 @@ def test_vtk_output():
     for domain_shape in [(4, 5), (3, 4, 5)]:
         dh = create_data_handling(domain_size=domain_shape, periodicity=True)
         vtk_output(dh)
+
+
+def test_add_arrays():
+    domain_shape = (3, 4, 5)
+    field_description = 'x, y(9)'
+
+    dh = create_data_handling(domain_size=domain_shape, default_ghost_layers=0, default_layout='numpy')
+    dh.add_arrays(field_description)
+
+    x, y = ps.fields(field_description + ': [3,4,5]')
+
+    assert x == dh.fields['x']
+    assert y == dh.fields['y']