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Implementation of Sketch-Based Anomaly Detection in Streaming Graphs paper

Overview

This repository contains an implementation, following River conventions, of the methods Anograph and AnoEdgeGlobal, specifically designed for edge anomaly detection. Methods are described in the paper Sketch-Based Anomaly Detection in Streaming Graphs by BHATIA, Siddharth, WADHWA, Mohit, KAWAGUCHI, Kenji, et al.

Usage

Hcms Class

Higher-order CMS (H-CMS) data structure implementation for anomaly detection.

Initialization

from AnoGraph import Hcms

# Create an instance of Hcms with specified parameters
hcms_instance = Hcms(r=2, b=32, d=None)

Methods

• hash(elem, i): Hash function used to determine the bucket for an element in a specific row.
• insert(a, b, weight): Inserts an edge (a, b) with a specified weight into the count matrix.
• decay(decay_factor): Applies decay to the entire count matrix to decrease counts over time.
• getAnoEdgeGlobalScore(src, dst): Computes the anomaly score for an edge (src, dst).
• getAnographScore(): Computes the global anomaly score for the entire count matrix.

Anograph Class

Anograph class for computing anomaly scores based on matrix density calculations.

Initialization

from AnoGraph import Anograph

# Create an instance of Anograph with specified parameters
anograph_instance = Anograph(time_window=30, edge_threshold=50, rows=2, buckets=32)

Methods

• learn_one(x): Update the Anograph instance with a new edge.
• get_score(): Get the current anomaly score.
• pickMinRow(mat, row_flag, col_flag): Pick the row with the minimum sum from the matrix.
• pickMinCol(mat, row_flag, col_flag): Pick the column with the minimum sum from the matrix.
• getMatrixDensity(mat, row_flag, col_flag): Compute the density of the submatrix specified by row_flag and col_flag.
• getAnographDensity(mat): Compute the Anograph density of the matrix.

AnoEdgeGlobal Class

Anomaly Detection using Edge Global Density.

Initialization

from AnoGraph import AnoEdgeGlobal

# Create an instance of AnoEdgeGlobal with specified parameters
ano_edge_global_instance = AnoEdgeGlobal(rows=2, buckets=32, decay_factor=0.9)

Methods

• learn_one(x): Update the AnoEdgeGlobal instance with a new edge.
• score_one(x): Calculate the anomaly score for a given edge.
• getAnoEdgeGlobalDensity(mat, src, dst): Calculate the density-based anomaly score for a specific edge.

Dependencies

• Python 3.x