From 2fdbb6422abe6eca715d87ba6daaf09992f0e93a Mon Sep 17 00:00:00 2001
From: Chris Johnson <chris.johnson@vaisala.com>
Date: Thu, 8 Aug 2024 19:53:53 -0700
Subject: [PATCH 1/2] adds round_to_int boolean argument to FixedScaleOffset to
 allow applying this filter without automatically converting to integers.
 (#549)

---
 numcodecs/fixedscaleoffset.py            | 12 ++++++++----
 numcodecs/tests/test_fixedscaleoffset.py | 11 ++++++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/numcodecs/fixedscaleoffset.py b/numcodecs/fixedscaleoffset.py
index b4d9469a..d632ebce 100644
--- a/numcodecs/fixedscaleoffset.py
+++ b/numcodecs/fixedscaleoffset.py
@@ -8,7 +8,7 @@
 class FixedScaleOffset(Codec):
     """Simplified version of the scale-offset filter available in HDF5.
     Applies the transformation `(x - offset) * scale` to all chunks. Results
-    are rounded to the nearest integer but are not packed according to the
+    are optionally rounded to the nearest integer but are not packed according to the
     minimum number of bits.
 
     Parameters
@@ -21,6 +21,8 @@ class FixedScaleOffset(Codec):
         Data type to use for decoded data.
     astype : dtype, optional
         Data type to use for encoded data.
+    round_to_int : boolean
+        Flag to control rounding encoded data to integers after applying scale and offset
 
     Notes
     -----
@@ -70,10 +72,11 @@ class FixedScaleOffset(Codec):
 
     codec_id = 'fixedscaleoffset'
 
-    def __init__(self, offset, scale, dtype, astype=None):
+    def __init__(self, offset, scale, dtype, astype=None, round_to_int=True):
         self.offset = offset
         self.scale = scale
         self.dtype = np.dtype(dtype)
+        self.round_to_int = round_to_int
         if astype is None:
             self.astype = self.dtype
         else:
@@ -91,8 +94,9 @@ def encode(self, buf):
         # compute scale offset
         enc = (arr - self.offset) * self.scale
 
-        # round to nearest integer
-        enc = np.around(enc)
+        if self.round_to_int:
+            # round to nearest integer
+            enc = np.around(enc)
 
         # convert dtype
         enc = enc.astype(self.astype, copy=False)
diff --git a/numcodecs/tests/test_fixedscaleoffset.py b/numcodecs/tests/test_fixedscaleoffset.py
index 8f985c4a..e8d2f379 100644
--- a/numcodecs/tests/test_fixedscaleoffset.py
+++ b/numcodecs/tests/test_fixedscaleoffset.py
@@ -2,7 +2,7 @@
 
 
 import numpy as np
-from numpy.testing import assert_array_equal
+from numpy.testing import assert_array_equal, assert_allclose
 import pytest
 
 
@@ -30,6 +30,7 @@
     FixedScaleOffset(offset=1000, scale=10**6, dtype='<f8', astype='<i4'),
     FixedScaleOffset(offset=1000, scale=10**12, dtype='<f8', astype='<i8'),
     FixedScaleOffset(offset=1000, scale=10**12, dtype='<f8'),
+    FixedScaleOffset(offset=1000, scale=10**12, dtype='<f8', round_to_int=False),
 ]
 
 
@@ -49,6 +50,14 @@ def test_encode():
     assert_array_equal(expect, actual)
     assert np.dtype(astype) == actual.dtype
 
+def test_encode_no_round():
+    dtype = '<f8'
+    astype = dtype
+    codec = FixedScaleOffset(scale=1, offset=1000, dtype=dtype, astype=astype, round_to_int=False)
+    arr = np.linspace(1000, 1001, 10, dtype=dtype)
+    expect = np.linspace(0, 1, 10, dtype=dtype)
+    actual = codec.encode(arr)
+    assert_allclose(expect, actual)
 
 def test_config():
     codec = FixedScaleOffset(dtype='<f8', astype='<i4', scale=10, offset=100)

From e26b7126ac49299db132994d5368659f4c5e0058 Mon Sep 17 00:00:00 2001
From: Chris Johnson <chris.johnson@vaisala.com>
Date: Thu, 8 Aug 2024 20:12:50 -0700
Subject: [PATCH 2/2] fix whitespace between test functions

---
 numcodecs/tests/test_fixedscaleoffset.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/numcodecs/tests/test_fixedscaleoffset.py b/numcodecs/tests/test_fixedscaleoffset.py
index e8d2f379..ece83d30 100644
--- a/numcodecs/tests/test_fixedscaleoffset.py
+++ b/numcodecs/tests/test_fixedscaleoffset.py
@@ -50,6 +50,7 @@ def test_encode():
     assert_array_equal(expect, actual)
     assert np.dtype(astype) == actual.dtype
 
+
 def test_encode_no_round():
     dtype = '<f8'
     astype = dtype
@@ -59,6 +60,7 @@ def test_encode_no_round():
     actual = codec.encode(arr)
     assert_allclose(expect, actual)
 
+
 def test_config():
     codec = FixedScaleOffset(dtype='<f8', astype='<i4', scale=10, offset=100)
     check_config(codec)