python_interface.md

Python interface

We have made an interface so you can use SPLINTER through Python. If you follow the instructions provided below you should be good to go in a matter of minutes (unless you choose to compile the library yourself). The interface has been tested and should work with both Python 2.7 and 3.x.

Setup

First, head to the releases tab and download a copy of splinter-python. Or, you can compile the library for yourself (as described in the documentation). After doing the step make install, you should have a directory structure that looks like this:

• main

  • lib
    • windows
      • x86
        • splinter-x-y.dll
      • x86-64
        • splinter-x-y.dll
    • linux
      • x86
        • libsplinter-x-y.so
      • x86-64
        • libsplinter-x-y.so
    • osx
      • x86
        • libsplinter-x-y.so
      • x86-64
        • libsplinter-x-y.so
  • include
    • cinterface.h
  • python
    • splinter
      • All files from the python directory in the repository

• The numbers in the filename (x-y) corresponds to the SPLINTER version, where x is the major and y is the minor version.

Make sure the folder called python is in your path, or that that folder is your current working directory. Then you can do import splinter and it should automatically load all classes along with the binary for you.

Basic usage

import splinter

# Example with one variable
def f1(x):
    return -1. + 2*x + 0.1*(x**2) + 10*np.random.rand(1)[0]

x = np.arange(0, 11, 1)
y = np.zeros((len(x),))
for i in range(len(x)):
    y[i] = f1(x[i])
data = list(zip(x, y))

# Build cubic B-spline that interpolates the data
bspline = splinter.BSplineBuilder(data, degree=3).build()

# Evaluate the B-spline
xd = np.arange(0, 10, .01)
yd = bspline.eval(xd)

# Save BSpline to file for loading it later:
bspline.save("myfile.myextension")

# Load BSpline from file:
loadedBSpline = splinter.BSpline("myfile.myextension")

Notice that if you are going to evaluate the BSpline in more than one point, it is preferred to call eval once, instead of n times.

More examples can be found in the directory /python/examples.

Please consult the documentation for the C++ version of the library if you still have unanswered questions after reading this document.