GRAPH ANALYSIS DEVICE, GRAPH ANALYSIS METHOD, AND GRAPH ANALYSIS PROGRAM
A conversion unit converts directions of edges between vertices in a graph to arguments on a complex plane. A generation unit generates a Hermitian matrix that represents a relationship between vertices in the graph by using the arguments converted by the conversion unit. A calculation unit calculates eigenvectors of the Hermitian matrix generated by the generation unit. A signal processing unit performs graph signal processing such as graph Fourier transform taking the eigenvectors calculated by the calculation unit to be a Fourier basis for a graph Laplacian.
1 . A graph analysis device comprising: a memory; and a processor coupled to the memory and programmed to execute a process comprising: converting directions of edges between vertices in a graph to arguments on a complex plane;
generating a Hermitian matrix that represents a relationship between vertices in the graph by using the arguments converted by the converting; and
calculating eigenvectors of the Hermitian matrix generated by the generating.
2 . The graph analysis device according to claim 1 , wherein
if the direction of an edge between vertices in the graph is a first direction, the converts the direction of the edge to a first angle, if the direction of the edge is opposite to the first direction, the converts the direction of the edge to an angle that is obtained by changing the sign of the first angle, and if the edge has no direction, the converting converts the direction of the edge to 0, and
the generating generates a matrix that is obtained by subtracting, from a degree matrix of the graph, a matrix of which rows and columns correspond to vertices in the graph and in which, if there is an edge between vertices that correspond to an element, the element is a complex number that has an argument converted by the converting and a constant absolute value.
3 . The graph analysis device according to claim 1 , further comprising
performing graph signal processing taking the eigenvectors calculated by the calculating to be a Fourier basis for a graph Laplacian.
4 . The graph analysis device according to claim 3 , wherein
the performing performs graph Fourier transform, graph filtering, or graph wavelet transform using the eigenvectors.
5 . A graph analysis method to be executed by a computer, the method comprising:
converting directions of edges between vertices in a graph to arguments on a complex plane;
generating a Hermitian matrix that represents a relationship between vertices in the graph by using the arguments converted in the converting, and
calculating eigenvectors of the Hermitian matrix generated in the generating.
6 . (canceled)
7 . A non-transitory computer-readable recording medium storing therein a graph analysis program that causes a computer to execute a process comprising:
converting directions of edges between vertices in a graph to arguments on a complex plane;
generating a Hermitian matrix that represents a relationship between vertices in the graph by using the arguments converted by the converting; and
calculating eigenvectors of the Hermitian matrix generated by the generating.