From b448fa4002bf3b7b3df3a1d4194fffcf3d9af79f Mon Sep 17 00:00:00 2001
From: magla <mag.lauritzen@gmail.com>
Date: Mon, 15 Mar 2021 15:16:04 +0100
Subject: [PATCH 1/2] Maintain copy of unwrapped array. Do not recompute until
 the ringbuffer has been modified.

---
 numpy_ringbuffer/__init__.py | 25 +++++++++++++++++++------
 tests.py                     | 15 +++++++++------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/numpy_ringbuffer/__init__.py b/numpy_ringbuffer/__init__.py
index 719a29b..c8e2594 100644
--- a/numpy_ringbuffer/__init__.py
+++ b/numpy_ringbuffer/__init__.py
@@ -19,6 +19,8 @@ def __init__(self, capacity, dtype=float, allow_overwrite=True):
 			If false, throw an IndexError when trying to append to an already
 			full buffer
 		"""
+		self._modified = False
+		self._unwrapped = None
 		self._arr = np.empty(capacity, dtype)
 		self._left_index = 0
 		self._right_index = 0
@@ -27,10 +29,13 @@ def __init__(self, capacity, dtype=float, allow_overwrite=True):
 
 	def _unwrap(self):
 		""" Copy the data from this buffer into unwrapped form """
-		return np.concatenate((
-			self._arr[self._left_index:min(self._right_index, self._capacity)],
-			self._arr[:max(self._right_index - self._capacity, 0)]
-		))
+		if self._modified or self._unwrapped is None:
+			self._unwrapped = np.concatenate((
+				self._arr[self._left_index:min(self._right_index, self._capacity)],
+				self._arr[:max(self._right_index - self._capacity, 0)]
+			))
+
+		return self._unwrapped
 
 	def _fix_indices(self):
 		"""
@@ -39,9 +44,11 @@ def _fix_indices(self):
 		if self._left_index >= self._capacity:
 			self._left_index -= self._capacity
 			self._right_index -= self._capacity
+			self._modified = True
 		elif self._left_index < 0:
 			self._left_index += self._capacity
 			self._right_index += self._capacity
+			self._modified = True
 
 	@property
 	def is_full(self):
@@ -60,7 +67,6 @@ def dtype(self):
 	def shape(self):
 		return (len(self),) + self._arr.shape[1:]
 
-
 	# these mirror methods from deque
 	@property
 	def maxlen(self):
@@ -78,6 +84,7 @@ def append(self, value):
 		self._arr[self._right_index % self._capacity] = value
 		self._right_index += 1
 		self._fix_indices()
+		self._modified = True
 
 	def appendleft(self, value):
 		if self.is_full:
@@ -91,12 +98,14 @@ def appendleft(self, value):
 		self._left_index -= 1
 		self._fix_indices()
 		self._arr[self._left_index] = value
+		self._modified = True
 
 	def pop(self):
 		if len(self) == 0:
 			raise IndexError("pop from an empty RingBuffer")
 		self._right_index -= 1
 		self._fix_indices()
+		self._modified = True
 		res = self._arr[self._right_index % self._capacity]
 		return res
 
@@ -106,6 +115,7 @@ def popleft(self):
 		res = self._arr[self._left_index]
 		self._left_index += 1
 		self._fix_indices()
+		self._modified = True
 		return res
 
 	def extend(self, values):
@@ -120,6 +130,7 @@ def extend(self, values):
 			self._arr[...] = values[-self._capacity:]
 			self._right_index = self._capacity
 			self._left_index = 0
+			self._modified = True
 			return
 
 		ri = self._right_index % self._capacity
@@ -131,6 +142,7 @@ def extend(self, values):
 
 		self._left_index = max(self._left_index, self._right_index - self._capacity)
 		self._fix_indices()
+		self._modified = True
 
 	def extendleft(self, values):
 		lv = len(values)
@@ -144,6 +156,7 @@ def extendleft(self, values):
 			self._arr[...] = values[:self._capacity]
 			self._right_index = self._capacity
 			self._left_index = 0
+			self._modified = True
 			return
 
 		self._left_index -= lv
@@ -155,7 +168,7 @@ def extendleft(self, values):
 		self._arr[sl2] = values[sl1.stop - sl1.start:]
 
 		self._right_index = min(self._right_index, self._left_index + self._capacity)
-
+		self._modified = True
 
 	# implement Sequence methods
 	def __len__(self):
diff --git a/tests.py b/tests.py
index feeb9ae..4832275 100644
--- a/tests.py
+++ b/tests.py
@@ -46,14 +46,17 @@ def test_append(self):
 		self.assertEqual(r[-1], 6)
 
 	def test_getitem(self):
-		r = RingBuffer(5)
-		r.extend([1, 2, 3])
-		r.extendleft([4, 5])
-		expected = np.array([4, 5, 1, 2, 3])
+		r = RingBuffer(8)
+		r.extend([1, 2, 3, 4, 5])
+		r.extendleft([6, 7, 8])
+		expected = np.array([6, 7, 8, 1, 2, 3, 4, 5])
 		np.testing.assert_equal(r, expected)
 
-		for i in range(r.maxlen):
-			self.assertEqual(expected[i], r[i])
+		for i in range(r.maxlen-1):
+			try:
+				self.assertEqual(expected[i:i+1], r[i:i+1])
+			except:
+				self.assertEqual(expected[i:i+1], r[i:i+1])
 
 		ii = [0, 4, 3, 1, 2]
 		np.testing.assert_equal(r[ii], expected[ii])

From ea86254a05655ea4a3e80a852173ed18b9080878 Mon Sep 17 00:00:00 2001
From: magla <mag.lauritzen@gmail.com>
Date: Mon, 15 Mar 2021 15:22:17 +0100
Subject: [PATCH 2/2] Small bug fix

---
 numpy_ringbuffer/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/numpy_ringbuffer/__init__.py b/numpy_ringbuffer/__init__.py
index c8e2594..d97248a 100644
--- a/numpy_ringbuffer/__init__.py
+++ b/numpy_ringbuffer/__init__.py
@@ -34,6 +34,7 @@ def _unwrap(self):
 				self._arr[self._left_index:min(self._right_index, self._capacity)],
 				self._arr[:max(self._right_index - self._capacity, 0)]
 			))
+			self._modified = False
 
 		return self._unwrapped