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author | S. Solomon Darnell | 2025-03-28 21:52:21 -0500 |
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committer | S. Solomon Darnell | 2025-03-28 21:52:21 -0500 |
commit | 4a52a71956a8d46fcb7294ac71734504bb09bcc2 (patch) | |
tree | ee3dc5af3b6313e921cd920906356f5d4febc4ed /.venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py | |
parent | cc961e04ba734dd72309fb548a2f97d67d578813 (diff) | |
download | gn-ai-master.tar.gz |
Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py b/.venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py new file mode 100644 index 00000000..079b1855 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/linalg/spectrum.py @@ -0,0 +1,186 @@ +""" +Eigenvalue spectrum of graphs. +""" + +import networkx as nx + +__all__ = [ + "laplacian_spectrum", + "adjacency_spectrum", + "modularity_spectrum", + "normalized_laplacian_spectrum", + "bethe_hessian_spectrum", +] + + +@nx._dispatchable(edge_attrs="weight") +def laplacian_spectrum(G, weight="weight"): + """Returns eigenvalues of the Laplacian of G + + Parameters + ---------- + G : graph + A NetworkX graph + + weight : string or None, optional (default='weight') + The edge data key used to compute each value in the matrix. + If None, then each edge has weight 1. + + Returns + ------- + evals : NumPy array + Eigenvalues + + Notes + ----- + For MultiGraph/MultiDiGraph, the edges weights are summed. + See :func:`~networkx.convert_matrix.to_numpy_array` for other options. + + See Also + -------- + laplacian_matrix + + Examples + -------- + The multiplicity of 0 as an eigenvalue of the laplacian matrix is equal + to the number of connected components of G. + + >>> G = nx.Graph() # Create a graph with 5 nodes and 3 connected components + >>> G.add_nodes_from(range(5)) + >>> G.add_edges_from([(0, 2), (3, 4)]) + >>> nx.laplacian_spectrum(G) + array([0., 0., 0., 2., 2.]) + + """ + import scipy as sp + + return sp.linalg.eigvalsh(nx.laplacian_matrix(G, weight=weight).todense()) + + +@nx._dispatchable(edge_attrs="weight") +def normalized_laplacian_spectrum(G, weight="weight"): + """Return eigenvalues of the normalized Laplacian of G + + Parameters + ---------- + G : graph + A NetworkX graph + + weight : string or None, optional (default='weight') + The edge data key used to compute each value in the matrix. + If None, then each edge has weight 1. + + Returns + ------- + evals : NumPy array + Eigenvalues + + Notes + ----- + For MultiGraph/MultiDiGraph, the edges weights are summed. + See to_numpy_array for other options. + + See Also + -------- + normalized_laplacian_matrix + """ + import scipy as sp + + return sp.linalg.eigvalsh( + nx.normalized_laplacian_matrix(G, weight=weight).todense() + ) + + +@nx._dispatchable(edge_attrs="weight") +def adjacency_spectrum(G, weight="weight"): + """Returns eigenvalues of the adjacency matrix of G. + + Parameters + ---------- + G : graph + A NetworkX graph + + weight : string or None, optional (default='weight') + The edge data key used to compute each value in the matrix. + If None, then each edge has weight 1. + + Returns + ------- + evals : NumPy array + Eigenvalues + + Notes + ----- + For MultiGraph/MultiDiGraph, the edges weights are summed. + See to_numpy_array for other options. + + See Also + -------- + adjacency_matrix + """ + import scipy as sp + + return sp.linalg.eigvals(nx.adjacency_matrix(G, weight=weight).todense()) + + +@nx._dispatchable +def modularity_spectrum(G): + """Returns eigenvalues of the modularity matrix of G. + + Parameters + ---------- + G : Graph + A NetworkX Graph or DiGraph + + Returns + ------- + evals : NumPy array + Eigenvalues + + See Also + -------- + modularity_matrix + + References + ---------- + .. [1] M. E. J. Newman, "Modularity and community structure in networks", + Proc. Natl. Acad. Sci. USA, vol. 103, pp. 8577-8582, 2006. + """ + import scipy as sp + + if G.is_directed(): + return sp.linalg.eigvals(nx.directed_modularity_matrix(G)) + else: + return sp.linalg.eigvals(nx.modularity_matrix(G)) + + +@nx._dispatchable +def bethe_hessian_spectrum(G, r=None): + """Returns eigenvalues of the Bethe Hessian matrix of G. + + Parameters + ---------- + G : Graph + A NetworkX Graph or DiGraph + + r : float + Regularizer parameter + + Returns + ------- + evals : NumPy array + Eigenvalues + + See Also + -------- + bethe_hessian_matrix + + References + ---------- + .. [1] A. Saade, F. Krzakala and L. Zdeborová + "Spectral clustering of graphs with the bethe hessian", + Advances in Neural Information Processing Systems. 2014. + """ + import scipy as sp + + return sp.linalg.eigvalsh(nx.bethe_hessian_matrix(G, r).todense()) |