The main interface to fetching full text is through `ft_get()`.

## Load fulltext

    library("fulltext")

## Structure of the returned object from ft_get()

Simple call, pass in a DOI and say where you want to get data from (by default, it's plos)

    res <- ft_get('10.1371/journal.pone.0086169', from = 'plos')

The article text and metadata is stored in the output object.

The `res` object is a list, with slots for each of the data sources, b/c you can request data from more than 1 data source.

    names(res)
    #> [1] "plos"          "entrez"        "elife"         "pensoft"       "arxiv"         "biorxiv"       "elsevier"      "sciencedirect" "wiley"

Let's dig into the `plos` source object, which is another list, including metadata the text data itself (in the `data` slot).

    res$plos
    #> $found
    #> [1] 1
    #>
    #> $dois
    #> [1] "10.1371/journal.pone.0086169"
    #>
    #> $data
    #> $data$backend
    #> [1] "ext"
    #>
    #> $data$cache_path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext"
    #>
    #> $data$path
    #> $data$path$`10.1371/journal.pone.0086169`
    #> $data$path$`10.1371/journal.pone.0086169`$path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext/10_1371_journal_pone_0086169.xml"
    #>
    #> $data$path$`10.1371/journal.pone.0086169`$id
    #> [1] "10.1371/journal.pone.0086169"
    #>
    #> $data$path$`10.1371/journal.pone.0086169`$type
    #> [1] "xml"
    #>
    #> $data$path$`10.1371/journal.pone.0086169`$error
    #> NULL
    #>
    #>
    #>
    #> $data$data
    #> NULL
    #>
    #>
    #> $opts
    #> $opts$doi
    #> [1] "10.1371/journal.pone.0086169"
    #>
    #> $opts$type
    #> [1] "xml"
    #>
    #> $opts$progress
    #> [1] FALSE
    #>
    #>
    #> $errors
    #>                             id error
    #> 1 10.1371/journal.pone.0086169  <NA>

Indexing to the `data` slot takes us to another list with metadata and the article

    res$plos$data
    #> $backend
    #> [1] "ext"
    #>
    #> $cache_path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext"
    #>
    #> $path
    #> $path$`10.1371/journal.pone.0086169`
    #> $path$`10.1371/journal.pone.0086169`$path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext/10_1371_journal_pone_0086169.xml"
    #>
    #> $path$`10.1371/journal.pone.0086169`$id
    #> [1] "10.1371/journal.pone.0086169"
    #>
    #> $path$`10.1371/journal.pone.0086169`$type
    #> [1] "xml"
    #>
    #> $path$`10.1371/journal.pone.0086169`$error
    #> NULL
    #>
    #>
    #>
    #> $data
    #> NULL

Going down one more index gets us the data object. There is no actual text as we have to collect it from the file on disk. See `ft_collect()` to get the text.

    res$plos$data
    #> $backend
    #> [1] "ext"
    #>
    #> $cache_path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext"
    #>
    #> $path
    #> $path$`10.1371/journal.pone.0086169`
    #> $path$`10.1371/journal.pone.0086169`$path
    #> [1] "/Users/sckott/Library/Caches/R/fulltext/10_1371_journal_pone_0086169.xml"
    #>
    #> $path$`10.1371/journal.pone.0086169`$id
    #> [1] "10.1371/journal.pone.0086169"
    #>
    #> $path$`10.1371/journal.pone.0086169`$type
    #> [1] "xml"
    #>
    #> $path$`10.1371/journal.pone.0086169`$error
    #> NULL
    #>
    #>
    #>
    #> $data
    #> NULL

## Fetching many articles

You can get a bunch of DOIs first, e.g., from PLOS using the `rplos` package

    library("rplos")
    (dois <- searchplos(q = "*:*", fl = 'id',
       fq = list('doc_type:full', "article_type:\"research article\""), limit = 5)$data$id)
    #> [1] "10.1371/journal.pone.0020843" "10.1371/journal.pone.0022257" "10.1371/journal.pone.0023139" "10.1371/journal.pone.0023138" "10.1371/journal.pone.0023119"
    ft_get(dois, from = 'plos')
    #> <fulltext text>
    #> [Docs] 5
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 10.1371/journal.pone.0020843 10.1371/journal.pone.0022257 10.1371/journal.pone.0023139 10.1371/journal.pone.0023138 10.1371/journal.pone.0023119 ...

## Different data sources

### Articles from eLife

One article

    ft_get('10.7554/eLife.04300', from = 'elife')
    #> <fulltext text>
    #> [Docs] 1
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 10.7554/eLife.04300 ...

Many articles

    ft_get(c('10.7554/eLife.04300','10.7554/eLife.03032'), from = 'elife')
    #> <fulltext text>
    #> [Docs] 2
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 10.7554/eLife.04300 10.7554/eLife.03032 ...

### Articles from Frontiers in Pharmacology (publisher: Frontiers)

    doi <- '10.3389/fphar.2014.00109'
    ft_get(doi, from = "entrez")
    #> <fulltext text>
    #> [Docs] 1
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 4050532 ...

## Search using ft_search()

For example, search entrez, get some DOIs, then fetch some articles

    (res <- ft_search(query = 'ecology', from = 'entrez'))
    #> Query:
    #>   [ecology]
    #> Found:
    #>   [PLoS: 0; BMC: 0; Crossref: 0; Entrez: 185437; arxiv: 0; biorxiv: 0; Europe PMC: 0; Scopus: 0; Microsoft: 0]
    #> Returned:
    #>   [PLoS: 0; BMC: 0; Crossref: 0; Entrez: 10; arxiv: 0; biorxiv: 0; Europe PMC: 0; Scopus: 0; Microsoft: 0]
    res$entrez$data$doi
    #>  [1] "10.3748/wjg.v25.i45.6579"    "10.1038/s41467-019-13800-3"  "10.7554/eLife.49826"         "10.5365/wpsar.2018.9.5.005"  "10.1038/s41598-019-55147-1"
    #>  [6] "10.1038/s41598-019-54857-w"  "10.1038/s41598-019-55028-7"  "10.1038/s41598-019-55204-9"  "10.5423/PPJ.OA.05.2019.0129" "10.5423/PPJ.NT.08.2019.0216"

Get articles

    ft_get(res$entrez$data$doi[1:3], from = 'entrez')
    #> <fulltext text>
    #> [Docs] 3
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 6906207 6904573 6904214 ...

## Collect full text from file on disk

When using `ft_get()` you write the files to disk, and you have to pull text out of them as a separate step.

    (res <- ft_get('10.1371/journal.pone.0086169', from = 'plos'))
    #> <fulltext text>
    #> [Docs] 1
    #> [Source] ext - /Users/sckott/Library/Caches/R/fulltext
    #> [IDs] 10.1371/journal.pone.0086169 ...

One way to do that is with `ft_collect()`. Before running `ft_collect()` the `data` slot is `NULL`.

    res$plos$data$data
    #> NULL

Run `ft_collect()`

    res <- res %>% ft_collect

After running `ft_collect()` the `data` slot has the text. If there's more than one article they are named by the identifier

    res$plos$data$data
    #> $`10.1371/journal.pone.0086169`
    #> {xml_document}
    #> <article article-type="research-article" dtd-version="3.0" lang="en" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">
    #> [1] <front>\n  <journal-meta>\n    <journal-id journal-id-type="nlm-ta">PLoS ONE</journal-id>\n    <journal-id journal-id-type="publisher-id">plos</journal-id>\n    <journal-id j ...
    #> [2] <body>\n  <sec id="s1">\n    <title>Introduction</title>\n    <p>Since the 1970s, biologists have directed substantial research effort to understanding adaptive sex-biased al ...
    #> [3] <back>\n  <ack>\n    <p>We thank Joan Silk, Julienne Rutherford, and two anonymous reviewers for their comments on earlier drafts of the manuscript.</p>\n  </ack>\n  <ref-lis ...