Google Scholar, OverLeaf, and

Gephi

Prof. Ralucca Gera, Applied Mathematics Dept.Naval Postgraduate SchoolMonterey, Californiargera@nps.edu

Excellence Through Knowledge

Google Scholar (https://scholar.google.com/)•

Google Scholar’s goals

• It enables searches of scholarly literature (scholarly publications, abstracts, books…).

• Easy to use (same familiar search bar as Google, but results are limited to scholarly resources).

• Contains links to the article’s PDF, Postscript, HTML format.

• Easy to view key information about articles: “cited by”, “related articles” and so on.

• Easy to export citation to LaTeX that can be used for any research formatting style.

Historical background

–Google Scholar was released (in beta) in 2004–Not the first freely available citation database

(CiteSeer, Scirus, etc)–Not subject specific

Many use it as a viable alternative to traditional citation databases such as Web of Science, since:

– Easy of use (free, no account needed)– Extensive coverage of articles– Encodes wide range of metrics about

articles/authors– However metrics are not perfect (data base is not

complete, some duplications exist, algorithms 4

Features of Google Scholar

• Searches all scholarly literature from one convenient place

• Explores related works, citations, authors, and publications

• Locates the complete document through your library or on the web

• Keeps up with recent developments in any area of research

• Checks who's citing your publications, creates a public author profile (if you get an account)

5Source: http://scholar.google.com/scholar/about.html#about

How are documents ranked?

“Google Scholar aims to rank documents the way researchers do, • weighing the full text of each document, • where it was published, • who it was written by, • as well as how often and how recently it has

been cited in other scholarly literature.”

6Source: http://scholar.google.com/scholar/about.html#about

H-index of a scientist from wikipedia

• A scholar with an index of h has published hpapers each of which has been cited in other papers at least h times

• The h-index of a publication is the largest number h such that at least h articles in that publication were cited at least h times each.

7Source: https://en.wikipedia.org/wiki/H-index

For example, a publication with five articles cited by 17, 9, 6, 3, and 2 papers respectively, has the h-index of 3.

Source: http://scholar.google.com/intl/en-US/scholar/metrics.html#metrics

Google Scholar Available Metrics

• The h-core of a publication is the set of top cited h articles from the publication. – For example, the publication above has the h-core with three

articles, those cited by 17, 9, and 6 in the list 17, 9, 6, 3, and 2 with the h-index 3.

• The h-median of a publication is the median of the citation counts in its h-core. – For the example before, the h-median of the publication was 9

(recall the references are 17, 9, 6, 3, and 2 times, of which17, 9, 6 are in the k-core).

• The h-median is a measure of the distribution of citations to the articles in the h-core.

8Source: http://scholar.google.com/intl/en-US/scholar/metrics.html#metrics

Google Scholar Available Metrics

• Finally, the h5-index, h5-core, and h5-median of a publication are, respectively, the h-index, h-core, and h-median of the articles that were published in the last 5 complete calendar years.

9Source: http://scholar.google.com/intl/en-US/scholar/metrics.html#metrics

Try Google Scholar now!

Excellence Through Knowledge

ShareLaTeX

• Free: https://www.overleaf.com/• OverLeaf is a web-based real-time collaborative

(like GoogleDocs) LaTeX editor (no need to download LaTeX on your machine)

• Documentation: https://www.overleaf.com/learn• Templates:

https://www.overleaf.com/latex/templates• Use it:www.overleaf.com (use your NPS email).

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Use your NPS email!

Synch it with the Dropbox and GitHub (the dropbox account must use the same email addressed use to create the overleaf account): 1. Click Account on the

upper right on the main site2. Account settings3. Log in4. Dropbox Integration

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Gephi Overview(https://gephi.org/)

Resources for Gephi:

• Overview and explanations of Gephi• Gephi’s overview tutorial• An introductory video to create data for Gephi

and to use degree, closeness and betweeness (also posted on the website unde today’s lecture).

• Gephi’s overview of layouts• Basic navigation

Layouts

• Layout choices (install plugins for more):Force directed (repulsion) ones:– Force Atalas 2 (It is focused on being useful to explore and get

meaning for real data, and a good readability, slow)– Yifan Hu (similar to FA2, fast, good for large graphs)– Fruchterman-Reingold (The nodes are the mass particles and the

edges are springs between the particles. The algorithms try to minimize the energy of this physical system. It has become a standard but remains very slow.)

– OpenOrd layout (good for communities)

Not force directed: – Expansion– Geographic map with GeoLayout 15

SAVE

• Once you have a visualization that you like, save the network, so that the next time you open it looks the same

• Cannot use undo in Gephi• When you run an analysis, save the network

each time with a different name • When you open part of a network on a new tab

in Gephi, save that as well.

16Try Gephi Now!

Preview Tab

• Click Preview next to the Data Laboratory, youmight like that view of thenetwork better:

• If you export, then this is what you export:

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Ranking nodes based on a statistic

• Once you ran a statistic (say degree) => size/color the nodes based on the ran statistic.

• Under on the topleft, choose Nodes andeither size or color

• Depending on the version you run, you will see:

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Filtering nodes based on a statistic

• Find Filters on the top right, next to Statistics

• Under topology, you can findthe centralities

• Choose one, drag and drop it to the Queries

• Choose the bounds needed.

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Export

• Take a screen shot using Snipping Tool, or• Export the visualized graph as SVG or PDF:

– Go to preview (fix if needed)– Resize for large networks– Click SVG

(SVG is vectorial graphics like PDF so they scale to different sizes nicely)

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Other statistics

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• Average path length: under the statics module, right

• Computes the average ofshortest paths between allpairs of nodes

• Result: