Cited by 1,826Complex Systems and Time Series AnalysisComplex Network Analysis TechniquesTime Series Analysis and Forecasting

The DOI matches its Crossref record; 22 of the 22 references it cites were found in a registry or an index; none of the 9 sources its claims cite is checked for support yet.

From time series to complex networks: the visibility graph

Open access
Lacasa, Lucas, Luque, Bartolo, Ballesteros, Fernando, Luque, Jordi, Nuño, Juan Carlos·2008·Proceedings of the National Academy of Sciences

Abstract

In this work we present a simple and fast computational method, the visibility algorithm , that converts a time series into a graph. The constructed graph inherits several properties of the series in its structure. Thereby, periodic series convert into regular graphs, and random series do so into random graphs. Moreover, fractal series convert into scale-free networks, enhancing the fact that power law degree distributions are related to fractality, something highly discussed recently. Some remarkable examples and analytical tools are outlined to test the method's reliability. Many different measures, recently developed in the complex network theory, could by means of this new approach characterize time series from a new point of view.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper introduces the visibility algorithm, which maps a time series into a graph by connecting data points that can “see” each other without intermediate heights blocking the line of sight. It shows that periodic series yield regular graphs, random series yield random graphs with exponential degree tails, and fractal series yield scale-free visibility graphs.

Key findings

  • Periodic time series map to regular graphs whose discrete degree distribution has peaks related to the series period; the example in Fig. 1 is a period-4 series.
  • A random series of \(10^6\) data from \(U[0,1]\) produces a visibility graph whose degree distribution has an exponential tail, attributed to rare large values acting as hubs.
  • Brownian motion visibility graphs are scale-free with \(P(k) \sim k^{-\alpha}\), \(\alpha = 2.00 \pm 0.01\), and show a Small-World effect with \(L(N) = 1.21 + 0.51\log(N)\).
  • Conway series visibility graphs are scale-free with \(\alpha = 1.2 \pm 0.1\) and scale-invariant path length \(L(N) = 0.76 N^{0.38}\); a deterministic fractal example is also shown analytically to yield a power-law degree distribution.

Methods

  • The visibility algorithm maps each time-series datum to a node and links two nodes if the straight line between their data values does not intersect any intermediate data height.
  • The paper analyzes periodic series, a random series of \(10^6\) points from \(U[0,1]\), Brownian motion of \(10^6\) data, a Conway series of \(4 \cdot 10^6\) data, and a deterministic iterated fractal series.
  • Main analyses include degree distributions \(P(k)\), mean path length \(L(N)\), and analytical recurrence relations for the deterministic fractal example.

Limitations

  • The paper states that information is inevitably lost because the network structure is completely determined by the binary adjacency matrix; for example, periodic series \(T_1 = \{\ldots,3,1,3,1,\ldots\}\) and \(T_2 = \{\ldots,3,2,3,2,\ldots\}\) have the same visibility graph despite being quantitatively different.
  • The paper states that it only tackles undirected graphs, while a directed version related to temporal axis direction is left for further work.
  • The paper notes that the simple deterministic fractal example does not provide a general explanation of why fractality translates into power-law distributions, though it may stand as a generic way to deal with deterministic fractal series generated by iteration.

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Integrity signals

Registry

Crossref · 10.1073/pnas.0709247105

Cites

22 of 22 references verified0 citation errors · 0 not checkable

Statistics

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Verification

Claims the paper makes

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  • It may state two separate claims as one. 6
  • Probably not a substantial claim. 3
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Citations

Cites

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Show all 22 references

Research works printed but not linked: 2

  1. J Conway Some Crazy Sequences, 1988).
  2. MA Stern J Reine Angew Math 55, 193–220 (1858).

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Metadata

Authors
Lacasa, L., Luque, B., Ballesteros, F., Luque, J., & Nuño, J. C.
Affiliations
  • Universidad Politécnica de Madrid (ES)
  • Universitat de València (ES)
  • Universitat Politècnica de Catalunya (ES)
Venue
Proceedings of the National Academy of Sciences
Published
2008-04
Volume
105
Issue
13
Pages
4972-4975
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2055538060
Cited by
1,826
References
22
Citations by year
2026: 102 · 2025: 180 · 2024: 149 · 2023: 156 · 2022: 157 · 2021: 151 · 2020: 157 · 2019: 154 · 2018: 137 · 2017: 105 · 2016: 84 · 2015: 60 · 2014: 61 · 2013: 47 · 2012: 51
FWCI
56.61
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • PubMed Central (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Social Sciences › Economics, Econometrics and Finance › Economics and Econometrics › Complex Systems and Time Series Analysis
  • Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Complex Network Analysis Techniques
  • Physical Sciences › Computer Science › Signal Processing › Time Series Analysis and Forecasting
Keywords
visibility graph, time series, complex networks, scale-free networks, power-law degree distribution, fractality, regular graphs, random graphs, network metrics, time series characterization

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