tolist() implementation

CHANGELOG.md

@@ -4,6 +4,7 @@
 - [#577](https://github.com/helmholtz-analytics/heat/pull/577) Add ndim property in dndarray
 - [#578](https://github.com/helmholtz-analytics/heat/pull/578) Bugfix: Bad variable in reshape
 - [#580](https://github.com/helmholtz-analytics/heat/pull/580) New feature: fliplr()
+- [#581](https://github.com/helmholtz-analytics/heat/pull/581) New Feature: DNDarray.tolist()
 - [#593](https://github.com/helmholtz-analytics/heat/pull/593) New feature arctan2()
 - [#594](https://github.com/helmholtz-analytics/heat/pull/594) New feature: Advanced indexing
 - [#594](https://github.com/helmholtz-analytics/heat/pull/594) Bugfix: getitem and setitem memory consumption heavily reduced

heat/core/dndarray.py

@@ -1,7 +1,10 @@
+from __future__ import annotations
+
 import numpy as np
 import math
 import torch
 import warnings
+from typing import List
 
 from . import arithmetics
 from . import devices
@@ -3459,6 +3462,36 @@ def tanh(self, out=None):
         """
         return trigonometrics.tanh(self, out)
 
+    def tolist(self, keepsplit=False) -> List:
+        """
+        Return a copy of the local array data as a (nested) Python list. For scalars, a standard Python number is returned.
+
+        Parameters
+        ----------
+        keepsplit: bool
+            Whether the list should be returned locally or globally.
+
+        Examples
+        --------
+        >>> a = ht.array([[0,1],[2,3]])
+        >>> a.tolist()
+        [[0, 1], [2, 3]]
+
+        >>> a = ht.array([[0,1],[2,3]], split=0)
+        >>> a.tolist()
+        [[0, 1], [2, 3]]
+
+        >>> a = ht.array([[0,1],[2,3]], split=1)
+        >>> a.tolist(keepsplit=True)
+        (1/2) [[0], [2]]
+        (2/2) [[1], [3]]
+        """
+
+        if not keepsplit:
+            return manipulations.resplit(self, axis=None).__array.tolist()
+
+        return self.__array.tolist()
+
     def transpose(self, axes=None):
         """
         Permute the dimensions of an array.

heat/core/tests/test_dndarray.py

@@ -1139,6 +1139,41 @@ def test_stride_and_strides(self):
         )
         self.assertEqual(heat_float64_F_split.strides, numpy_float64_F_split_strides)
 
+    def test_tolist(self):
+        a = ht.zeros([ht.MPI_WORLD.size, ht.MPI_WORLD.size, ht.MPI_WORLD.size], dtype=ht.int32)
+        res = [
+            [[0 for z in range(ht.MPI_WORLD.size)] for y in range(ht.MPI_WORLD.size)]
+            for x in range(ht.MPI_WORLD.size)
+        ]
+        self.assertListEqual(a.tolist(), res)
+
+        a = ht.zeros(
+            [ht.MPI_WORLD.size, ht.MPI_WORLD.size, ht.MPI_WORLD.size], dtype=ht.int32, split=0
+        )
+        res = [
+            [[0 for z in range(ht.MPI_WORLD.size)] for y in range(ht.MPI_WORLD.size)]
+            for x in range(ht.MPI_WORLD.size)
+        ]
+        self.assertListEqual(a.tolist(), res)
+
+        a = ht.zeros(
+            [ht.MPI_WORLD.size, ht.MPI_WORLD.size, ht.MPI_WORLD.size], dtype=ht.float32, split=1
+        )
+        res = [
+            [[0.0 for z in range(ht.MPI_WORLD.size)] for y in [ht.MPI_WORLD.rank]]
+            for x in range(ht.MPI_WORLD.size)
+        ]
+        self.assertListEqual(a.tolist(keepsplit=True), res)
+
+        a = ht.zeros(
+            [ht.MPI_WORLD.size, ht.MPI_WORLD.size, ht.MPI_WORLD.size], dtype=ht.bool, split=2
+        )
+        res = [
+            [[False for z in [ht.MPI_WORLD.rank]] for y in range(ht.MPI_WORLD.size)]
+            for x in range(ht.MPI_WORLD.size)
+        ]
+        self.assertListEqual(a.tolist(keepsplit=True), res)
+
     def test_xor(self):
         int16_tensor = ht.array([[1, 1], [2, 2]], dtype=ht.int16, device=ht_device)
         int16_vector = ht.array([[3, 4]], dtype=ht.int16, device=ht_device)