Mercurial > repos > shellac > sam_consensus_v3
annotate env/share/doc/networkx-2.5/examples/algorithms/plot_rcm.py @ 0:4f3585e2f14b draft default tip
"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"
author | shellac |
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date | Mon, 22 Mar 2021 18:12:50 +0000 |
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1 """ |
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2 === |
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3 Rcm |
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4 === |
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5 |
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6 Cuthill-McKee ordering of matrices |
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7 |
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8 The reverse Cuthill-McKee algorithm gives a sparse matrix ordering that |
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9 reduces the matrix bandwidth. |
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10 """ |
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11 |
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12 import networkx as nx |
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13 from networkx.utils import reverse_cuthill_mckee_ordering |
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14 import numpy as np |
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15 |
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16 # build low-bandwidth numpy matrix |
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17 G = nx.grid_2d_graph(3, 3) |
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18 rcm = list(reverse_cuthill_mckee_ordering(G)) |
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19 print("ordering", rcm) |
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20 |
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21 print("unordered Laplacian matrix") |
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22 A = nx.laplacian_matrix(G) |
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23 x, y = np.nonzero(A) |
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24 # print(f"lower bandwidth: {(y - x).max()}") |
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25 # print(f"upper bandwidth: {(x - y).max()}") |
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26 print(f"bandwidth: {(y - x).max() + (x - y).max() + 1}") |
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27 print(A) |
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28 |
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29 B = nx.laplacian_matrix(G, nodelist=rcm) |
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30 print("low-bandwidth Laplacian matrix") |
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31 x, y = np.nonzero(B) |
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32 # print(f"lower bandwidth: {(y - x).max()}") |
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33 # print(f"upper bandwidth: {(x - y).max()}") |
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34 print(f"bandwidth: {(y - x).max() + (x - y).max() + 1}") |
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35 print(B) |