electrum

commit 30ffb3d4dca5a0f42473d8e2bd065049d5943e50
parent 1ebfcc0f364ecb806c0ce736a76de8a3256748fd
Author: SomberNight <somber.night@protonmail.com>
Date:   Sun, 26 May 2019 04:10:32 +0200

util: add function "chunks"

taken from ElectrumX
https://github.com/kyuupichan/electrumx/blob/67111a3c4c812d0550fdba013ac886ad824689df/electrumx/lib/util.py#L149

Diffstat:
M
electrum/tests/test_util.py
 | 
8
+++++++-
M
electrum/util.py
 | 
8
++++++++

2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/electrum/tests/test_util.py b/electrum/tests/test_util.py
@@ -1,7 +1,7 @@
 from decimal import Decimal
 
 from electrum.util import (format_satoshis, format_fee_satoshis, parse_URI,
-                           is_hash256_str)
+                           is_hash256_str, chunks)
 
 from . import SequentialTestCase
 
@@ -104,3 +104,9 @@ class TestUtil(SequentialTestCase):
         self.assertFalse(is_hash256_str('qweqwe'))
         self.assertFalse(is_hash256_str(None))
         self.assertFalse(is_hash256_str(7))
+
+    def test_chunks(self):
+        self.assertEqual([[1, 2], [3, 4], [5]],
+                         list(chunks([1, 2, 3, 4, 5], 2)))
+        with self.assertRaises(ValueError):
+            list(chunks([1, 2, 3], 0))
diff --git a/electrum/util.py b/electrum/util.py
@@ -520,6 +520,14 @@ def is_non_negative_integer(val) -> bool:
     return False
 
 
+def chunks(items, size: int):
+    """Break up items, an iterable, into chunks of length size."""
+    if size < 1:
+        raise ValueError(f"size must be positive, not {repr(size)}")
+    for i in range(0, len(items), size):
+        yield items[i: i + size]
+
+
 def format_satoshis_plain(x, decimal_point = 8):
     """Display a satoshi amount scaled.  Always uses a '.' as a decimal
     point and has no thousands separator"""