1 files changed, 75 insertions, 0 deletions
diff --git a/circuitpython/extmod/ulab/snippets/rclass.py b/circuitpython/extmod/ulab/snippets/rclass.py
new file mode 100644
index 0000000..cb95021
--- /dev/null
+++ b/circuitpython/extmod/ulab/snippets/rclass.py
@@ -0,0 +1,75 @@
+from typing import List, Tuple, Union  # upip.install("pycopy-typing")
+from ulab import numpy as np
+
+_DType = int
+_RClassKeyType = Union[slice, int, float, list, tuple, np.ndarray]
+
+# this is a stripped down version of RClass (used by np.r_[...etc])
+# it doesn't include support for string arguments as the first index element
+class RClass:
+
+    def __getitem__(self, key: Union[_RClassKeyType, Tuple[_RClassKeyType, ...]]):
+
+        if not isinstance(key, tuple):
+            key = (key,)
+
+        objs: List[np.ndarray] = []
+        scalars: List[int] = []
+        arraytypes: List[_DType] = []
+        scalartypes: List[_DType] = []
+
+        # these may get overridden in following loop
+        axis = 0
+
+        for idx, item in enumerate(key):
+            scalar = False
+
+            try:
+                if isinstance(item, np.ndarray):
+                    newobj = item
+
+                elif isinstance(item, slice):
+                    step = item.step
+                    start = item.start
+                    stop = item.stop
+                    if start is None:
+                        start = 0
+                    if step is None:
+                        step = 1
+                    if isinstance(step, complex):
+                        size = int(abs(step))
+                        newobj: np.ndarray = np.linspace(start, stop, num=size)
+                    else:
+                        newobj = np.arange(start, stop, step)
+
+                # if is number
+                elif isinstance(item, (int, float, bool)):
+                    newobj = np.array([item])
+                    scalars.append(len(objs))
+                    scalar = True
+                    scalartypes.append(newobj.dtype())
+                    
+                else:
+                    newobj = np.array(item)
+                    
+            except TypeError:
+                raise Exception("index object %s of type %s is not supported by r_[]" % (
+                    str(item), type(item)))
+
+            objs.append(newobj)
+            if not scalar and isinstance(newobj, np.ndarray):
+                arraytypes.append(newobj.dtype())
+
+        # Ensure that scalars won't up-cast unless warranted
+        final_dtype = min(arraytypes + scalartypes)
+        for idx, obj in enumerate(objs):
+            if obj.dtype != final_dtype:
+                objs[idx] = np.array(objs[idx], dtype=final_dtype)
+
+        return np.concatenate(tuple(objs), axis=axis)
+
+    # this seems weird - not sure what it's for
+    def __len__(self):
+        return 0
+        
+r_ = RClass()