Data Serialization

Data serialization is an important component of the cross-platform design of the COMPAS code base, since it is the basis for data transfer during Remote Procedure Calls with compas.rpc.

It is also the preferred mechanism for writing COMPAS data to files such that it can be retrieved at a later point in time, or even store information about entire work sessions during iterative processes.

The mechanism is based on serialization to JSON to ensure maximum compatibility with various use cases and circumstances. All COMPAS data objects (geometry and data structures) implement the interface provided by compas.base.Base, which forces them to define the methods and properties that form the backbone of the serialization infrastructure.

• compas.base.Base.to_data()

• compas.base.Base.from_data()

• compas.base.Base.to_json()

• compas.base.Base.from_json()

The “from” methods are class methods (@classmethod) and act as alternative constructors. The “to” methods are their counterparts that produce compatible data from object instances.

# to data

import compas
from compas.datastructures import Mesh

mesh1 = Mesh()

a = mesh1.add_vertex(x=0, y=0, z=0)
b = mesh1.add_vertex(x=1, y=0, z=0)
c = mesh1.add_vertex(x=1, y=1, z=0)
d = mesh1.add_vertex(x=0, y=1, z=0)

mesh1.add_face([a, b, c, d])

data = mesh1.to_data()

# from data

mesh2 = Mesh.from_data(data)

# to json

import math
import compas
from compas.geometry import Point, Vector
from compas.geometry import Frame, Rotation, Translation
from compas.geometry import Box

box = Box(Frame.worldXY(), 1, 1, 1)

R = Rotation.from_axis_angle_vector(Vector(0, 0, 1), math.radians(45))
T = Translation.from_vector(Vector(2, 0, 0))
X = T * R

box.transform(X)

compas.json_dump([box, X], 'data.json')

# from json

import compas
from compas.geometry import Transformation

box, X = compas.json_load('data.json')

T = Transformation.from_frame(box.frame)

print(T == X)

box.transform(T.inverse())

print(box.frame.point)
print(box.frame.xaxis)
print(box.frame.yaxis)
print(box.frame.zaxis)