# Get started with rmangal

#### Steve Vissault & Kevin Cazelles

#### 2019-09-28

# Context

## The Mangal project

The Mangal project aims at archiving published ecological networks and at easing their retrieval. To do so, Mangal:

1. uses a data specification for ecological networks (described in Poisot et al. 2016);

2. archives ecological networks in a PostgreSQL database;

3. provides:

- a data explorer to visualize and download data available;
- a RESTful Application Programming Interface (API);
- a client library for Julia: Mangal.jl;
- a client of this API for R: the rmangal package described below.

Currently, 172 datasets are including in the database representing over 1300 ecological networks. In 2016, the first paper describing the project was published and introduced the first release of rmangal (Poisot et al. 2016). Since then, the structure of the database has been improved (new fields have been added), several ecological networks added and the API entirely rewritten. Consequently, the first release of the rmangal is obsolete (and archived) and we introduce rmangal v2.0 in this vignette.

## Data structure

The diagram on the left side represents the structure of the Mangal database. All references included in Mangal correspond to a specific publication that includes one or several dataset(s). This dataset is basically a collection of ecological networks whose nodes and interactions (edges) are stored in separate tables. Below, we briefly describe the content of each table.

References – Information pertaining to a reference (scientific article, book, online website, etc.) characterizing an original collection of ecological networks. URLs of data and publication sources are included as well as persistent identifiers (when available) such as digital object identifiers (DOIs). This allows the user to retrieve more details about original publications using appropriate R packages such as crossref.

Datasets – Metadata of the datasets attached to a reference. It includes a general description of the networks.

Networks – Metadata of the networks attached to a dataset. It provides the sampling location, date and specific description of the network.

Nodes – Information on the population, taxa or individu in the network. Each node has the original taxon name documented and taxonomic backbone provided by all services embedded in taxize (Chamberlain et al. 2019).

Interactions – Information on the interaction type (e.g. mutualism, predation, etc.), the strength, and the direction of the interaction between two nodes.

## Authentication

So far, the `rmangal` package provides methods to get access to the data store. Data requests (performed via `httr::GET()`) do not require any authentication.

A bearer authentication strategy using ORCID credentials (as a third-party services) has been implemented on all `POST`, `DELETE`, `PUT` API operations to allow the user to add and delete new ecological to the data base. These features are not currently included in the rmangal package, but are under consideration for future major releases.

# How to use rmangal

## Overall approach

In order to efficiently retrieve networks from the database, rmangal includes 7 search functions querying the 5 tables described above as well as a table dedicated to the taxonomy backbone.

1. `search_references()`: search in the reference table, for instance the user can look for a specific `doi`;
2. `search_datasets()`: search among datasets using a keyword;
3. `search_networks()` and `search_networks_sf()`: search networks based on a keyword or a geographical area;
4. `search_interactions()`: list all networks containing a specific interaction type;
5. `search_nodes()`: identify nodes based on nodes information;
6. `search_taxonomy()`: identify nodes based on taxonomic names and unique identifiers.

All of these functions return specific class objects with the information needed to retrieve the corresponding set of ecological networks with `get_collection()`. Hence, the user can easily retrieve data in two steps:

    networks <- search_*() %>% get_collection()

Note that if there is only one network to be retrieved, `get_collection()` returns a `mgNetwork` object, otherwise it returns an object of class `mgNetworksCollection` which is a collection (a list) of `mgNetwork` objects. Below, we exemplify how to use the search functions, how to get a collection of networks and how to use other packages to carry out specific analyses.

## Search functions

In rmangal, every functions queries a specific table and allow only one query at a time (see section Batch analysis to learn how to perform more than one query). All the functions offer two ways to query the corresponding table:

1. a keyword: in this case, the entries returned are the partial or full keyword match of any strings contained in the table;
2. a custom query: in this case, entries returned are exact matches.

Let’s load rmangal as well as two helper packages:

    library(rmangal)
    library(magrittr) # for the pipe %>%
    library(tibble) # to use tibble (enhanced data frames)

### Search and list available datasets

Let’s assume we are looking for ecological networks including species living in lagoons. If we have no idea about any existing data set, the best starting point is then to query the `dataset` table with `lagoon` as a keyword:

    lagoon <- search_datasets(query = "lagoon")
    class(lagoon)
    #> [1] "tbl_df"           "tbl"              "data.frame"
    #> [4] "mgSearchDatasets"
    lagoon
    #> # A tibble: 2 x 10
    #>      id name  description public created_at updated_at ref_id user_id
    #>   <int> <chr> <chr>       <lgl>  <chr>      <chr>       <int>   <int>
    #> 1    22 zeti… Dietary ma… TRUE   2019-02-2… 2019-02-2…     22       3
    #> 2    52 yane… Food web o… TRUE   2019-02-2… 2019-02-2…     53       3
    #> # … with 2 more variables: references <list>, networks <list>

If the Mangal reference id containing the lagoon networks was known, we could build a custom query as follow:

    lagoon_zetina <- search_datasets(list(ref_id = 22))
    lagoon_zetina
    #> # A tibble: 1 x 10
    #>      id name  description public created_at updated_at ref_id user_id
    #>   <int> <chr> <chr>       <lgl>  <chr>      <chr>       <int>   <int>
    #> 1    22 zeti… Dietary ma… TRUE   2019-02-2… 2019-02-2…     22       3
    #> # … with 2 more variables: references <list>, networks <list>

Note that if an empty character is passed, i.e. `""`, all entries are returned. We can use this behavior to list all datasets available:

    all_datasets <- search_datasets("")
    glimpse(all_datasets)
    #> Observations: 172
    #> Variables: 10
    #> $ id          <int> 2, 7, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,…
    #> $ name        <chr> "howking_1968", "lundgren_olesen_2005", "elberling_o…
    #> $ description <chr> "Insect activity recorded on flower at Lake Hazen, E…
    #> $ public      <lgl> TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE…
    #> $ created_at  <chr> "2019-02-22T15:39:00.427Z", "2019-02-22T20:04:25.322…
    #> $ updated_at  <chr> "2019-02-22T15:39:00.427Z", "2019-02-22T20:04:25.322…
    #> $ ref_id      <int> 2, 7, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,…
    #> $ user_id     <int> 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3…
    #> $ references  <list> [<data.frame[1 x 11]>, <data.frame[1 x 11]>, <data.…
    #> $ networks    <list> [<data.frame[1 x 13]>, <data.frame[1 x 13]>, <data.…

As shown in the diagram above, a dataset comes from a specific reference and `search_references()` queries the reference table directly. A handy argument of this function is `doi` as it allows to pass a Digital Object Identifier and so to retrieve all datasets attached to a specific publication.

    zetina_2003 <- search_references(doi = "10.1016/s0272-7714(02)00410-9")

### Finding a specific network

We can also search by keyword across all networks.

    insect_coll <- search_networks(query="insect%")
    glimpse(insect_coll)
    #> Observations: 14
    #> Variables: 13
    #> $ id               <int> 18, 909, 948, 1460, 1461, 1471, 1493, 1501, 150…
    #> $ name             <chr> "mosquin_martin_1967_19650731_18", "elberling_o…
    #> $ date             <chr> "1965-07-31T00:00:00.000Z", "1994-08-23T00:00:0…
    #> $ description      <chr> "Occurence of flower-visiting insect on plant s…
    #> $ public           <lgl> TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE,…
    #> $ all_interactions <lgl> FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE…
    #> $ created_at       <chr> "2019-02-22T18:38:37.491Z", "2019-02-24T22:21:3…
    #> $ updated_at       <chr> "2019-02-22T18:38:37.491Z", "2019-02-24T22:21:3…
    #> $ dataset_id       <int> 4, 9, 66, 91, 91, 99, 114, 118, 118, 119, 124, …
    #> $ user_id          <int> 3, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
    #> $ geom_type        <chr> "Point", "Point", "Point", "Point", "Point", "P…
    #> $ geom_lon         <list> [-114.9667, 18.5, 138.3833, -85.09443, -83.508…
    #> $ geom_lat         <list> [75, 68.35, 35.5833, 10.4568, 8.534018, 9.9339…

It is also possible to retrieve all networks based on interaction types involved:

    # List all interaction types available
    avail_type()
    #>  [1] "competition"  "amensalism"   "neutralism"   "commensalism"
    #>  [5] "mutualism"    "parasitism"   "predation"    "herbivory"
    #>  [9] "symbiosis"    "scavenger"    "detritivore"  "unspecified"
    comp_interac <- search_interactions(type="competition")
    # Number of competition interactions in mangal
    nrow(comp_interac)
    #> [1] 12

`search_networks_sf()` handles spatial queries: argument `query_sf` takes a `sf` object as input and returns all networks included in the spatial extent of this object. For instance, one can retrieve all Californian networks included in Mangal like so:

    library(sf)
    library(mapview)
    library(USAboundaries)
    area <- us_states(state = "california")
    in_CA <- search_networks_sf(area)

    mapView(in_CA, legend = FALSE) + mapview(sf::st_cast(area,"MULTILINESTRING"), color = "red", legend = FALSE)

### Search for a specific taxon

The user can easily identify networks including a specific taxonomic entity with `search_taxonomy()`:

    sr_ficus <- search_taxonomy("Ficus")

This function allows to search for a specific taxonomic entity using it’s validated name or unique identifiers, i.e. EOL, TSN, GBIF, COL, BOLD and NCBI IDs. Taxon names of the `taxonomy` table were validated with TNRS (see http://tnrs.iplantcollaborative.org/ and/or GNR (see https://resolver.globalnames.org/). The taxon names in this table might not be the taxon name documented in the original publication. In order to identify relevant networks with the original name, use [search_nodes()].

The validation of taxon names was performed by an automated procedure using taxize (Chamberlain et al. 2019) and if there is any doubt, the original names recorded by authors should be regarded as the most reliable information. Please report any issue related to taxonomy at https://github.com/mangal-wg/mangal-datasets/issues.

    glimpse(search_taxonomy(tsn = 28749))
    #> Observations: 1
    #> Variables: 18
    #> $ id                  <int> 2629
    #> $ original_name       <chr> "Acer negundo"
    #> $ node_level          <chr> "taxon"
    #> $ network_id          <int> 19
    #> $ taxonomy_id         <int> 2
    #> $ created_at          <chr> "2019-02-22T18:48:49.433Z"
    #> $ updated_at          <chr> "2019-02-22T18:48:49.433Z"
    #> $ taxonomy.id         <int> 2
    #> $ taxonomy.name       <chr> "Acer negundo"
    #> $ taxonomy.ncbi       <int> 4023
    #> $ taxonomy.tsn        <int> 28749
    #> $ taxonomy.eol        <int> 583069
    #> $ taxonomy.bold       <int> 100987
    #> $ taxonomy.gbif       <int> 3189866
    #> $ taxonomy.col        <chr> "90203e29e2f59e5754167f89b9eba3cc"
    #> $ taxonomy.rank       <chr> "species"
    #> $ taxonomy.created_at <chr> "2019-02-21T21:17:12.585Z"
    #> $ taxonomy.updated_at <chr> "2019-06-14T15:20:36.273Z"
    glimpse(search_taxonomy(eol = 583069))
    #> Observations: 1
    #> Variables: 18
    #> $ id                  <int> 2629
    #> $ original_name       <chr> "Acer negundo"
    #> $ node_level          <chr> "taxon"
    #> $ network_id          <int> 19
    #> $ taxonomy_id         <int> 2
    #> $ created_at          <chr> "2019-02-22T18:48:49.433Z"
    #> $ updated_at          <chr> "2019-02-22T18:48:49.433Z"
    #> $ taxonomy.id         <int> 2
    #> $ taxonomy.name       <chr> "Acer negundo"
    #> $ taxonomy.ncbi       <int> 4023
    #> $ taxonomy.tsn        <int> 28749
    #> $ taxonomy.eol        <int> 583069
    #> $ taxonomy.bold       <int> 100987
    #> $ taxonomy.gbif       <int> 3189866
    #> $ taxonomy.col        <chr> "90203e29e2f59e5754167f89b9eba3cc"
    #> $ taxonomy.rank       <chr> "species"
    #> $ taxonomy.created_at <chr> "2019-02-21T21:17:12.585Z"
    #> $ taxonomy.updated_at <chr> "2019-06-14T15:20:36.273Z"

Note that in some case, one may need to find a dataset based on the original name included in the publication, in such case, `search_nodes()` must be used:

    sr_ficus2 <- search_nodes("Ficus")

## Get networks associated with a `search_*` object

Once the search performed, ecological networks are accessible from the object returned with `get_collection()`:

    nets_lagoons <- lagoon %>% get_collection
    nets_in_CA <- in_CA %>% get_collection
    nets_competition <- comp_interac %>% get_collection

    nets_lagoons
    #> A collection of 3 networks
    #>
    #> * Network # included in data set #
    #> * Description: Dietary matrix of the Huizache–Caimanero lagoon
    #> * Includes 189 edges and 26 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 81%, BOLD: 81%, EOL: 85%, COL: 81%, GBIF: 0%, NCBI: 85%
    #> * Published in ref # DOI:10.1016/s0272-7714(02)00410-9
    #>
    #> * Network # included in data set #
    #> * Description: Food web of the Brackish lagoon
    #> * Includes 27 edges and 11 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 45%, BOLD: 45%, EOL: 45%, COL: 45%, GBIF: 18%, NCBI: 45%
    #> * Published in ref # DOI:NA
    #>
    #> * Network # included in data set #
    #> * Description: Food web of the Costal lagoon
    #> * Includes 34 edges and 13 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 54%, BOLD: 54%, EOL: 54%, COL: 54%, GBIF: 15%, NCBI: 54%
    #> * Published in ref # DOI:NA
    class(nets_lagoons)
    #> [1] "mgNetworksCollection"

Note that `mgNetworksCollection` objects are lists of `mgNetwork` object which are a list of five datasets reflecting the 5 tables presented in the diagram in the first section:

    names(nets_lagoons[[1]])
    #> [1] "network"      "nodes"        "interactions" "dataset"
    #> [5] "reference"
    glimpse(nets_lagoons[[1]]$network)
    #> Observations: 1
    #> Variables: 13
    #> $ network_id       <int> 86
    #> $ name             <chr> "zetina_2003_20030101_86"
    #> $ date             <chr> "2003-01-01T00:00:00.000Z"
    #> $ description      <chr> "Dietary matrix of the Huizache–Caimanero lagoo…
    #> $ public           <lgl> TRUE
    #> $ all_interactions <lgl> FALSE
    #> $ created_at       <chr> "2019-02-23T17:04:34.046Z"
    #> $ updated_at       <chr> "2019-02-23T17:04:34.046Z"
    #> $ dataset_id       <int> 22
    #> $ user_id          <int> 3
    #> $ geom_type        <chr> "Point"
    #> $ geom_lon         <list> [-106.1099]
    #> $ geom_lat         <list> [22.98531]
    glimpse(nets_lagoons[[1]]$nodes)
    #> Observations: 26
    #> Variables: 19
    #> $ node_id             <int> 4904, 4905, 4906, 4907, 4908, 4909, 4910, 49…
    #> $ original_name       <chr> "Scianids", "Elopids", "Lutjanids", "Carangi…
    #> $ node_level          <chr> "taxon", "taxon", "taxon", "taxon", "taxon",…
    #> $ network_id          <int> 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, …
    #> $ taxonomy_id         <int> 4363, 4364, 4365, 4366, 4367, 4368, 4369, 43…
    #> $ created_at          <chr> "2019-02-23T17:04:42.505Z", "2019-02-23T17:0…
    #> $ updated_at          <chr> "2019-02-23T17:04:42.505Z", "2019-02-23T17:0…
    #> $ taxonomy.id         <int> 4363, 4364, 4365, 4366, 4367, 4368, 4369, 43…
    #> $ taxonomy.name       <chr> "Sciaenidae", "Elops", "Lutjanidae", "Carang…
    #> $ taxonomy.ncbi       <int> 30870, 7927, 30850, 8157, 8184, 31017, 30840…
    #> $ taxonomy.tsn        <int> 169237, 28630, 168845, 168584, 167642, 43998…
    #> $ taxonomy.eol        <int> 5211, 46561210, 5294, 5361, 5355, 5115, 5317…
    #> $ taxonomy.bold       <int> 1856, 4061, 1858, 1851, 586, 1313, 1855, 112…
    #> $ taxonomy.gbif       <lgl> NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, …
    #> $ taxonomy.col        <chr> "81a86c329909d507edb5c296906ef3f4", "94532a1…
    #> $ taxonomy.rank       <chr> "family", "genus", "family", "family", "fami…
    #> $ taxonomy.created_at <chr> "2019-02-23T17:04:35.620Z", "2019-02-23T17:0…
    #> $ taxonomy.updated_at <chr> "2019-06-14T15:25:46.438Z", "2019-06-14T15:2…
    #> $ taxonomy            <lgl> NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, …
    glimpse(nets_lagoons[[1]]$edges)
    #>  NULL
    glimpse(nets_lagoons[[1]]$dataset)
    #> Observations: 1
    #> Variables: 8
    #> $ dataset_id  <int> 22
    #> $ name        <chr> "zetina_2003"
    #> $ description <chr> "Dietary matrix of the Huizache–Caimanero lagoon"
    #> $ public      <lgl> TRUE
    #> $ created_at  <chr> "2019-02-23T17:04:32.017Z"
    #> $ updated_at  <chr> "2019-02-23T17:04:32.017Z"
    #> $ ref_id      <int> 22
    #> $ user_id     <int> 3
    glimpse(nets_lagoons[[1]]$reference)
    #> Observations: 1
    #> Variables: 11
    #> $ ref_id       <int> 22
    #> $ doi          <chr> "10.1016/s0272-7714(02)00410-9"
    #> $ first_author <chr> "manuel j. zetina-rejon"
    #> $ year         <chr> "2003"
    #> $ jstor        <lgl> NA
    #> $ pmid         <lgl> NA
    #> $ bibtex       <chr> "@article{Zetina_Rej_n_2003, doi = {10.1016/s0272-7…
    #> $ paper_url    <chr> "https://doi.org/10.1016%2Fs0272-7714%2802%2900410-…
    #> $ data_url     <chr> "https://globalwebdb.com/"
    #> $ created_at   <chr> "2019-02-23T17:04:28.307Z"
    #> $ updated_at   <chr> "2019-02-23T17:04:28.307Z"

# Integrated workflow with rmangal

## Batch analysis

So far, the search functions of rmangal allow the user to perform only a single search at a time. The simplest way to do more than one search is to loop over a vector or a list of queries. Below we exemplify how to do so using `lapply()`:

    tsn <- c(837855, 169237)
    mgn <- lapply(tsn, function(x) search_taxonomy(tsn = x)) %>%
      lapply(get_collection) %>%
      combine_mgNetworks
    mgn
    #> A collection of 3 networks
    #>
    #> * Network # included in data set #
    #> * Description: Flower and anthophilous insect interactions in the primary cool-temperate subalpine forests and meadows at Mt. Kushigata, Yamanashi Prefecture, Japan
    #> * Includes 871 edges and 456 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 55%, BOLD: 33%, EOL: 80%, COL: 77%, GBIF: 35%, NCBI: 73%
    #> * Published in ref # DOI:NA
    #>
    #> * Network # included in data set #
    #> * Description: Dietary matrix of the Huizache–Caimanero lagoon
    #> * Includes 189 edges and 26 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 81%, BOLD: 81%, EOL: 85%, COL: 81%, GBIF: 0%, NCBI: 85%
    #> * Published in ref # DOI:10.1016/s0272-7714(02)00410-9
    #>
    #> * Network # included in data set #
    #> * Description: Food web of the Angolan fishery landings
    #> * Includes 127 edges and 28 nodes
    #> * Current taxonomic IDs coverage for nodes of this network:
    #>   --> ITIS: 61%, BOLD: 50%, EOL: 61%, COL: 54%, GBIF: 4%, NCBI: 57%
    #> * Published in ref # DOI:10.3989/scimar.2011.75n2309

## Geolocalize Mangal networks with `sf`

The function `get_collection()` has an argument `as_sf` than converts network metadata of mgNetwork objects to `sf` objects, which requires `sf` to be installed. This allows the user to easily geolocalize the networks retrieved from Mangal.

    # assuming sf and mapview are is loaded (as we did above)
    mg_lag_sf <- search_datasets(query = 'lagoon') %>% get_collection(as_sf = TRUE)
    class(mg_lag_sf[[1]]$network)
    #> [1] "sf"         "data.frame"
    # let's combine all these sf object into a single one
    mapView(mg_lag_sf[[1]]$network) + mapView(mg_lag_sf[[2]]$network)

## Taxonomic analysis with `taxize`

As Mangal includes taxonomic identifiers, rmangal can readily be combined with `taxize` (see taxize for more details about this package):

    library(taxize)
    tsn_acer <- search_taxonomy("Acer")$taxonomy.tsn
    classification(tsn_acer, db = "itis")
    #> $`28749`
    #>               name          rank     id
    #> 1          Plantae       kingdom 202422
    #> 2    Viridiplantae    subkingdom 954898
    #> 3     Streptophyta  infrakingdom 846494
    #> 4      Embryophyta superdivision 954900
    #> 5     Tracheophyta      division 846496
    #> 6  Spermatophytina   subdivision 846504
    #> 7    Magnoliopsida         class  18063
    #> 8          Rosanae    superorder 846548
    #> 9       Sapindales         order  28643
    #> 10     Sapindaceae        family  28657
    #> 11            Acer         genus  28727
    #> 12    Acer negundo       species  28749
    #>
    #> $`28757`
    #>                name          rank     id
    #> 1           Plantae       kingdom 202422
    #> 2     Viridiplantae    subkingdom 954898
    #> 3      Streptophyta  infrakingdom 846494
    #> 4       Embryophyta superdivision 954900
    #> 5      Tracheophyta      division 846496
    #> 6   Spermatophytina   subdivision 846504
    #> 7     Magnoliopsida         class  18063
    #> 8           Rosanae    superorder 846548
    #> 9        Sapindales         order  28643
    #> 10      Sapindaceae        family  28657
    #> 11             Acer         genus  28727
    #> 12 Acer saccharinum       species  28757
    #>
    #> $<NA>
    #> [1] NA
    #>
    #> $<NA>
    #> [1] NA
    #>
    #> $`837855`
    #>               name          rank     id
    #> 1          Plantae       kingdom 202422
    #> 2    Viridiplantae    subkingdom 954898
    #> 3     Streptophyta  infrakingdom 846494
    #> 4      Embryophyta superdivision 954900
    #> 5     Tracheophyta      division 846496
    #> 6  Spermatophytina   subdivision 846504
    #> 7    Magnoliopsida         class  18063
    #> 8          Rosanae    superorder 846548
    #> 9       Sapindales         order  28643
    #> 10     Sapindaceae        family  28657
    #> 11            Acer         genus  28727
    #> 12  Acer japonicum       species 837855
    #>
    #> attr(,"class")
    #> [1] "classification"
    #> attr(,"db")
    #> [1] "itis"

## Network analysis with `igraph`

Once the data are retrieved and a `mgNetwork` or a `mgNetworkCollection` objects obtained, it is straightforward to convert it as a `igraph` (see the dedicated website) object and then to carry out network analysis:

    library(igraph)
    mg_lagoons <- search_datasets(query = 'lagoon') %>% get_collection
    # NB the line below returns a list of igraph objects
    ig_lagoons <- as.igraph(mg_lagoons)
    ## Modularity analysis for the first network
    modularity(ig_lagoons[[1]], membership(cluster_walktrap(ig_lagoons[[1]])))
    #> [1] 0.04824893
    ## Degree values for all networks
    lapply(ig_lagoons, degree)
    #> [[1]]
    #> 4904 4905 4906 4907 4908 4909 4910 4911 4912 4913 4914 4915 4916 4917 4918
    #>   17   11   14   13   18   20   14   10   18   14   12   15    7   15   14
    #> 4919 4920 4921 4922 4924 4925 4926 4927 4923 4929 4928
    #>   12   14   11   26    7   22   15   21   16    5   17
    #>
    #> [[2]]
    #> 6459 6460 6461 6463 6464 6465 6458 6462 6466 6456 6457
    #>    4    7    9    3    3    7    4    6    3    4    4
    #>
    #> [[3]]
    #> 6445 6447 6448 6449 6450 6452 6453 6454 6446 6451 6455 6443 6444
    #>    6    4    5    5   11    2    5    8    3    5    4    5    5

## Network manipulation and visualization with `tidygraph` and `ggraph`

The package `tidygraph` treats networks as two tidy tables (one for the edges and one for the nodes) that can be modified using the grammar of data manipulation developed in the tidyverse. Moreover, `tidygraph` wraps over most of the `igraph` functions so that the user can call a vast variety of algorithms to properly analysis networks. Fortunately, objects of class `mgNetwork` can readily be converted into `tbl_graph` objects which allows the user to benefit from all the tools included in `tidygraph`:

    library(tidygraph)
    # NB the line below would not work with a mgNetworksCollection (use lapply)
    tg_lagoons <-  as_tbl_graph(mg_lagoons[[1]]) %>%
      mutate(centrality_dg = centrality_degree(mode = 'in'))
    tg_lagoons %E>% as_tibble
    #> # A tibble: 189 x 19
    #>     from    to interaction_id date  direction type  method attr_id value
    #>    <int> <int>          <int> <chr> <chr>     <chr> <lgl>    <int> <dbl>
    #>  1     9     9          48376 2003… directed  pred… NA          12 0.026
    #>  2     9    11          48377 2003… directed  pred… NA          12 0.025
    #>  3     9    12          48378 2003… directed  pred… NA          12 0.003
    #>  4     9    15          48379 2003… directed  pred… NA          12 0.009
    #>  5     9    16          48380 2003… directed  pred… NA          12 0.009
    #>  6     9    17          48381 2003… directed  pred… NA          12 0.016
    #>  7     9    18          48382 2003… directed  pred… NA          12 0.284
    #>  8     9    19          48383 2003… directed  pred… NA          12 0.231
    #>  9     9    21          48384 2003… directed  pred… NA          12 0.079
    #> 10     9    22          48385 2003… directed  pred… NA          12 0.09
    #> # … with 179 more rows, and 10 more variables: public <lgl>,
    #> #   network_id <int>, created_at <chr>, updated_at <chr>,
    #> #   attribute.id <int>, attribute.name <chr>, attribute.description <chr>,
    #> #   attribute.unit <lgl>, attribute.created_at <chr>,
    #> #   attribute.updated_at <chr>
    tg_lagoons %N>% as_tibble %>%
      select(original_name, taxonomy.tsn, centrality_dg)
    #> # A tibble: 26 x 3
    #>    original_name  taxonomy.tsn centrality_dg
    #>    <chr>                 <int>         <dbl>
    #>  1 Scianids             169237             1
    #>  2 Elopids               28630             0
    #>  3 Lutjanids            168845             1
    #>  4 Carangids            168584             2
    #>  5 Centropomids         167642             2
    #>  6 Ariids                43998             1
    #>  7 Haemulids            169055             4
    #>  8 Pleuronectoids       172859             3
    #>  9 Callinectes           13951             6
    #> 10 Belonoids            165546             4
    #> # … with 16 more rows

Another strong advantage of `tbl_graph` objects is that there are the objects used by the package `ggraph` that that offers various functions (theme, geoms, etc.) to efficiently visualize networks:

    library(ggraph)
    ggraph(tg_lagoons, layout = "stress") +
      geom_edge_parallel(end_cap = circle(.5), start_cap = circle(.5),
            arrow = arrow(length = unit(1, 'mm'), type = 'closed')) +
      geom_node_point(aes(colour = taxonomy.rank), size = 8) +
      theme_graph(background = "grey40", foreground = NA, text_colour = 'white')

## Creating a list references for a set of networks

We can easily print the BibTeX of all publications involved in the networks collection.

    # library(RefManageR)
    # tmpf <- tempfile(, fileext = ".bib")
    search_datasets(query = 'lagoon') %>%
      get_collection %>% get_citation %>% cat(sep = "\n")
    #> @article{Zetina_Rej_n_2003, doi = {10.1016/s0272-7714(02)00410-9}, url = {https://doi.org/10.1016%2Fs0272-7714%2802%2900410-9}, year = 2003, month = {aug}, publisher = {Elsevier {BV}}, volume = {57}, number = {5-6}, pages = {803--815}, author = {Manuel J. Zetina-Rejón and Francisco Arreguí-Sánchez and Ernesto A. Chávez}, title = {Trophic structure and flows of energy in the Huizache{   extendash}Caimanero lagoon complex on the Pacific coast of Mexico},journal = {Estuarine, Coastal and Shelf Science}}
    #> @book{yanez_1978, Author = {Yáñez-Arancibia, Alejandro}, Editor = {Universidad Nacional Autónoma de México, Centro de Ciencias del Mar y Limnología. Ciudad Universitaria, México, D.F. -- 1a ed.},Title = {Taxonomía, ecología y estructura de las comunidades de peces en lagunas costeras con bocas efímeras del Pacífico de México}, Year = {1978}}
    # file = tmpf)
    # ReadBib(tmpf)

## References

Chamberlain, Scott, Eduard Szoecs, Zachary Foster, Zebulun Arendsee, Carl Boettiger, Karthik Ram, Ignasi Bartomeus, et al. 2019. Taxize: Taxonomic Information from Around the Web. https://github.com/ropensci/taxize.

Poisot, Timothée, Benjamin Baiser, Jennifer A. Dunne, Sonia Kéfi, François Massol, Nicolas Mouquet, Tamara N. Romanuk, Daniel B. Stouffer, Spencer A. Wood, and Dominique Gravel. 2016. “Mangal - Making Ecological Network Analysis Simple.” Ecography 39 (4): 384–90. https://doi.org/10.1111/ecog.00976.