20080618a.py

"""Given a weighted adjacency matrix, calculate the path resistance matrix.

Here the weighted adjacency matrix is the conductance matrix.
Each element is the reciprocal of the value of a resistor
directly connecting the nodes.
"""

import numpy as np

from SnippetUtil import HandlingError
import MatrixUtil
import Euclid
import Form
import FormOut

def get_form():
    """
    @return: the body of a form
    """
    A = np.array([
        [0, 2, 2, 0, 0, 0, 0],
        [2, 0, 2, 0, 0, 0, 0],
        [2, 2, 0, 3, 0, 0, 0],
        [0, 0, 3, 0, 2, 2, 0],
        [0, 0, 0, 2, 0, 2, 1],
        [0, 0, 0, 2, 2, 0, 1],
        [0, 0, 0, 0, 1, 1, 0]])
    form_objects = [
            Form.Matrix('matrix', 'weighted adjacency matrix',
                A, MatrixUtil.assert_weighted_adjacency)]
    return form_objects

def get_form_out():
    return FormOut.Matrix()

def get_response_content(fs):
    A = fs.matrix
    L = Euclid.adjacency_to_laplacian(A)
    D = Euclid.laplacian_to_edm(L)
    return MatrixUtil.m_to_string(D) + '\n'