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some optimizations for rescaleData (#1518)

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1) use float32 instead of float64 for low precision inputs
2) use in-place operations to avoid unnecessary copies
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pijyoi 2021-01-31 06:38:34 +08:00 committed by GitHub
parent 56ee690d58
commit 9d89d10bcf
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1 changed files with 11 additions and 5 deletions
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16
pyqtgraph/functions.py
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@ -951,7 +951,12 @@ def rescaleData(data, scale, offset, dtype=None, clip=None):
else:
dtype = np.dtype(dtype)
d2 = data.astype(np.float) - float(offset)
if np.can_cast(data, np.float32):
work_dtype = np.float32
else:
work_dtype = np.float64
d2 = data.astype(work_dtype, copy=True)
d2 -= offset
d2 *= scale
# Clip before converting dtype to avoid overflow
@ -959,13 +964,14 @@ def rescaleData(data, scale, offset, dtype=None, clip=None):
lim = np.iinfo(dtype)
if clip is None:
# don't let rescale cause integer overflow
d2 = np.clip(d2, lim.min, lim.max)
np.clip(d2, lim.min, lim.max, out=d2)
else:
d2 = np.clip(d2, max(clip[0], lim.min), min(clip[1], lim.max))
np.clip(d2, max(clip[0], lim.min), min(clip[1], lim.max), out=d2)
else:
if clip is not None:
d2 = np.clip(d2, *clip)
data = d2.astype(dtype)
np.clip(d2, *clip, out=d2)
# don't copy if no change in dtype
data = d2.astype(dtype, copy=False)
return data