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\alias{nexusDatasetInfo}
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\alias{print.nexusDatasetInfo}
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\alias{print.nexusDatasetInfoList}
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\alias{summary.nexusDatasetInfoList}
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\concept{The Nexus network repository}
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\title{Query and download from the Nexus network repository}
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\description{The Nexus network repository is an online collection of
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network data sets. These functions can be used to query it and
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download data from it, directly as an igraph graph.}
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nexus.list(tags=NULL, offset=0, limit=10,
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operator=c("or", "and"),
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order=c("date", "name", "popularity"),
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nexus.url=getIgraphOpt("nexus.url"))
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nexus.info(id, nexus.url=getIgraphOpt("nexus.url"))
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nexus.get(id, offset=0, order=c("date", "name", "popularity"),
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nexus.url=getIgraphOpt("nexus.url"))
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nexus.search(q, offset=0, limit=10,
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order=c("date", "name", "popularity"),
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nexus.url=getIgraphOpt("nexus.url"))
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\method{print}{nexusDatasetInfo}(x, \dots)
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\method{summary}{nexusDatasetInfoList}(object, \dots)
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\method{print}{nexusDatasetInfoList}(x, \dots)
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\item{tags}{A character vector, the tags that are searched. If not
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given (or \code{NULL}), then all datasets are listed.}
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\item{offset}{An offset to select part of the results. Results are
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listed from \code{offset}+1.}
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\item{limit}{The maximum number of results to return.}
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\item{operator}{A character scalar. If \sQuote{or} (the default),
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then all datasets that have at least one of the given tags, are
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returned. If it if \sQuote{and}, then only datasets that have all
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the given tags, are returned.}
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\item{order}{The ordering of the results, possible values are:
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\sQuote{date}, \sQuote{name}, \sQuote{popularity}.}
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\item{id}{The numeric or character id of the data set to query or
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download. Instead of the data set ids, it is possible to supply a
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\code{nexusDatasetInfo} or \code{nexusDatasetInfoList} object
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here directly and then the query is done on the corresponding data
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\item{q}{Nexus search string. See examples below. For the complete
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documentation please see the Nexus homepage at
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\url{http://nexus.igraph.org}.}
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\item{nexus.url}{The URL of the Nexus server. Don't change this from
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the default, unless you set up your own Nexus server.}
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\item{x,object}{The \code{nexusDatasetInfo} object to print.}
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\item{\dots}{Currently ignored.}
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Nexus is an online repository of networks, with an API that allow
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programatic queries against it, and programatic data download as
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The \code{nexus.list} and \code{nexus.info} functions query the
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online database. They both return \code{nexusDatasetInfo} objects.
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\code{nexus.info} returns more information than \code{nexus.list}.
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\code{nexus.search} searches Nexus, and returns a list of data sets,
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as \code{nexusDatasetInfo} objects. See below for some search
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\code{nexus.get} downloads a data set from Nexus, based on its numeric
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id, or based on a Nexus search string. For search strings, only the
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first search hit is downloaded, but see also the \code{offset}
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argument. (If there are not data sets found, then the function returns
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The \code{nexusDatasetInfo} objects returned by \code{nexus.list} have
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\item{id}{The numeric id of the dataset.}
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\item{sid}{The character id of the dataset.}
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\item{name}{Character scalar, the name of the dataset.}
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\item{vertices/edges}{Character, the number of vertices and edges in
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the graph(s). Vertices and edges are separated by a slash, and
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if the data set consists of multiple networks, then they are
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\item{tags}{Character vector, the tags of the dataset. Directed
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graph have the tags \sQuote{directed}. Undirected graphs are
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tagged as \sQuote{undirected}. Other common tags are:
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\sQuote{weighted}, \sQuote{bipartite}, \sQuote{social network},
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\item{networks}{The ids and names of the networks in the data
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set. The numeric and character id are separated by a slash, and
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multiple networks are separated by spaces.}
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\code{nexusDatasetInfo} objects returned by \code{nexus.info} have the
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following additional fields:
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\item{date}{Character scalar, e.g. \sQuote{2011-01-09}, the date
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when the dataset was added to the database.}
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\item{formats}{Character vector, the data formats in which the data
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set is available. The various formats are separated by semicolons.}
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\item{licence}{Character scalar, the licence of the dataset.}
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\item{licence url}{Character scalar, the URL of the licence of the
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dataset. Pleaase make sure you consult this before using a
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\item{summary}{Character scalar, the short description of
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the dataset, this is usually a single sentence.}
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\item{description}{Character scalar, the full description of the
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\item{citation}{Character scalar, the paper(s) describing the
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dataset. Please cite these papers if you are using the dataset in
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your research, the licence of most datasets requires this.}
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\item{attributes}{A list of lists, each list entry is a graph,
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vertex or edge attribute and has the following entries:
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\item{type}{Type of the attribute, either \sQuote{graph},
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\sQuote{vertex} or \sQuote{edge}.}
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\item{datatype}{Data type of the attribute, currently it can be
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\sQuote{numeric} and \sQuote{string}.}
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\item{name}{Character scalar, the name of the attribute.}
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\item{description}{Character scalar, the description of the
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The results of the Nexus queries are printed to the screen in a
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consise format, similar to the format of igraph graphs. A data set
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list (typically the result of \code{nexus.list} and
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\code{nexus.search}) looks like this: \preformatted{NEXUS 1-5/18 -- data set list
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[1] kaptail.4 39/109-223 #18 Kapferer tailor shop
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[2] condmatcollab2003 31163/120029 #17 Condensed matter collaborations+
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[3] condmatcollab 16726/47594 #16 Condensed matter collaborations+
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[4] powergrid 4941/6594 #15 Western US power grid
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[5] celegansneural 297/2359 #14 C. Elegans neural network }
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Each line here represents a data set, and the following information is
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given about them: the character id of the data set
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(e.g. \code{kaptail} or \code{powergrid}), the number of vertices and
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number of edges in the graph of the data sets. For data sets with
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multiple graphs, intervals are given here. Then the numeric id of the
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data set and the reamining space is filled with the name of the data
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Summary information about an individual Nexus data set is printed
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as \preformatted{NEXUS B--- 39 109-223 #18 kaptail -- Kapferer tailor shop
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+ tags: directed; social network; undirected
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+ nets: 1/KAPFTI2; 2/KAPFTS2; 3/KAPFTI1; 4/KAPFTS1}
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This is very similar to the header that is used for printing igraph
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graphs, but there are some differences as well. The four characters
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after the \code{NEXUS} word give the most important properties of the
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graph(s): the first is \sQuote{\code{U}} for undirected and
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\sQuote{\code{D}} for directed graphs, and \sQuote{\code{B}} if the
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data set contains both directed and undirected graphs. The second is
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\sQuote{\code{N}} named graphs. The third character is
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\sQuote{\code{W}} for weighted graphs, the fourth is \sQuote{\code{B}}
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if the data set contains bipartite graphs. Then the number of vertices
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and number of edges are printed, for data sets with multiple graphs,
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the smallest and the largest values are given. Then comes the numeric
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id, and the string id of the data set. The end of the first
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line contains the name of the data set. The second row
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lists the data set tags, and the third row the networks that are
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included in the data set.
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Detailed data set information is printed similarly, but it contains
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\code{nexus.list} and \code{nexus.search} return a list of
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\code{nexusDatasetInfo} objects. The list also has these attributes:
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\item{size}{The number of data sets returned by the query.}
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\item{totalsize}{The total number of data sets found for the query.}
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\item{offset}{The offset parameter of the query.}
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\item{limit}{The limit parameter of the query.}
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\code{nexus.info} returns a single \code{nexusDatasetInfo} object.
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\code{nexus.get} returns an igraph graph object, or a list of graph
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objects, if the data set consists of multiple networks.
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\author{Gabor Csardi \email{csardi.gabor@gmail.com}}
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\seealso{ \url{http://nexus.igraph.org} }
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\dontrun{nexus.list(tag="weighted")
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nexus.list(limit=3, order="name")
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nexus.list(limit=3, order="name")[[1]]
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## Data sets related to 'US':
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## Search for data sets that have 'network' in their name:
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nexus.search("name:network")
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## Any word can match
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nexus.search("blog or US or karate")
added
removed
interfaces/R/igraph/man/nexus.Rd
