Loading and Saving Data

NURBS-Python provides the following methods for loading curve and surface data from a file:

• BSpline.Curve.load() and NURBS.Curve.load()
• BSpline.Surface.load() and NURBS.Surface.load()

Additionally, save functionality is provided via the following methods:

• BSpline.Curve.save() and NURBS.Curve.save()
• BSpline.Surface.save() and NURBS.Surface.save()

These functions implement Python’s pickle module to serialize the degree, knot vector and the control points data. The idea behind this system is only to provide users a basic data persistence capability, not to introduce a new file type. Since the data is pickled, it can be loaded with any compatible Python version even without using any special library.

The following example demonstrates the save functionality on a curve:

from geomdl import BSpline
from geomdl import utilities
from geomdl import exchange

# Create a B-Spline curve instance
curve = BSpline.Curve()

# Set the degree
curve.degree = 3

# Load control points from a text file
curve.ctrlpts = exchange.import_txt("control_points.txt")

# Auto-generate the knot vector
curve.knotvector = utilities.generate_knot_vector(curve.degree, len(curve.ctrlpts))

# Save the curve
curve.save("mycurve.pickle")

The saved curve can be loaded from the file with the following simple code segment:

from geomdl import BSpline

# Create a B-Spline curve instance
curve2 = BSpline.Curve()

# Load the saved curve from a file
curve2.load("mycurve.pickle")

Since the load-save functionality implements Python’s pickle module, the saved file can also be loaded directly without using the NURBS-Python library.

import pickle

# "data" variable will be a dictionary containing the curve information
data = pickle.load(open("mycurve.pickle"), "rb")

The pickle module has its own limitations by its design. Please see the Python documentation for more details.