Implement `partition_all` function

Issue:
https://github.com/genenetwork/gn-gemtext-threads/blob/main/topics/gn1-migration-to-gn2/partial-correlations.gmi

* gn3/data_helpers.py: new function (partition_all)
* tests/unit/test_data_helpers.py: tests for function
  `gn3.data_helpers.partition_all`

  As part of migrating some functions that access the database, this commit
  extracts generic processes that can be accomplished on data, and implements
  the `partition_all` function, that is equivalent to Clojure's
  `partition-all` function.

1 files changed, 25 insertions, 0 deletions

diff --git a/gn3/data_helpers.py b/gn3/data_helpers.py
new file mode 100644
index 0000000..f0d971e
--- /dev/null
+++ b/gn3/data_helpers.py
@@ -0,0 +1,25 @@
+"""
+This module will hold generic functions that can operate on a wide-array of
+data structures.
+"""
+
+from math import ceil
+from functools import reduce
+from typing import Any, Tuple, Sequence
+
+def partition_all(num: int, items: Sequence[Any]) -> Tuple[Tuple[Any, ...], ...]:
+    """
+    Given a sequence `items`, return a new sequence of the same type as `items`
+    with the data partitioned into sections of `n` items per partition.
+
+    This is an approximation of clojure's `partition-all` function.
+    """
+    def __compute_start_stop__(acc, iteration):
+        start = iteration * num
+        return acc + ((start, start + num),)
+
+    iterations = range(ceil(len(items) / num))
+    return tuple([# type: ignore[misc]
+        tuple(items[start:stop]) for start, stop # type: ignore[has-type]
+        in reduce(
+            __compute_start_stop__, iterations, tuple())])