A fast cubic spline interpolator for equally spaced values and complex data.
There are two reasons why fcSpline should be used instead of scipy.interpolate.CubicSpline.
- When called in a loop, fcSpline it 3 to 5 time faster than CubicSpline (see
fcs_timing.py). - Natively handles complex data.
What are the drawbacks? Well, fcSpline works on equally spaced data only. At the moment it supports 64-floats and 128-bit compex-values (however, generalization should be trivial).
from fastcubicspline import FCS
# set up x-limits
x_low = 1
x_high = 5
# set up the y-data, here complex values
y_data = [9+9j, 4+4j, 0, 6+6j, 2+2j]
# class init
fcs = FCS(x_low, x_high, y_data)
# simply call the FCS-object like a regular function
# to get interpolated values
print(fcs(2.5))
# (0.921875+0.921875j)For convenience, this package also provides a polynomial interpolator. Note that the NPointPoly class is not intended for time crucial applications.
from fastcubicspline import NPointPoly
# the x and y values
x = [1, 2, 4, 5, 8]
y = [9 + 9j, 4 + 4j, 0, 6 + 6j, 2 + 2j]
npp = NPointPoly(x, y)
# call the NPointPoly-object to get interpolated value at any x
print(npp(2.5))(see also examples/examples.py)
There is not much of an API, so there is no extra documentation page. Everything is, however, documented by means of function annotations and doc-strings within the code and should be visible when developing in a modern IDE.
fastcubicspline is on PyPi. So you can simply install the latest release with
pip install fastcubicspline
Fetch the latest version (or check any previous stage) by cloning from https://github.com/cimatosa/fcSpline.
Make sure pip is installed. Change into the fcSpline package directory and run:
python -m pip install .
See the option --user if you don't have the appropriate permission
for an installation to the standard location.
Change into the fcSpline package directory.
Install fastcubicspline and its dependencies into a virtual environment with
poetry install
and spawn a shell using that environment poetry shell.
Now you can check if the tests pass with pytest.
poetry install should build the cython extension which you cen check with pytest -v -k cython.
In case of poetry errors, you might want to get the latest poetry version
with poetry self update.
Some distutils magic is contained in build_ext.py so you can simply call
python3 build_ext.py
to build the Cython extension inplace.
Run pytest -v -k cython to verify that the Cython extension is available.
Clean the build files by calling
python3 build_ext.py clean
Run and list all tests with
pytest -v
* Press, W.H., Teukolsky, S.A., Vetterling, W.T., Flannery, B.P., 2007.
Numerical Recipes 3rd Edition: The Art of Scientific Computing,
Auflage: 3. ed. Cambridge University Press, Cambridge, UK; New York.
* Wikipedia, Retrieved September 1, 2023, from
https://en.wikipedia.org/wiki/Finite_difference_coefficient#Forward_finite_difference
Copyright (c) 2023 Richard Hartmann
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