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rplos introduction
=====

```{r echo=FALSE}
knitr::opts_chunk$set(
  comment = "#>", 
  warning = FALSE, 
  message = FALSE
)
```

The `rplos` package interacts with the API services of [PLoS](http://www.plos.org/) 
(Public Library of Science) Journals. You used to need an API key to work with 
this package - that is no longer needed!

This tutorial will go through three use cases to demonstrate the kinds
of things possible in `rplos`.

* Search across PLoS papers in various sections of papers
* Search for terms and visualize results as a histogram OR as a plot through 
time
* Text mining of scientific literature

### Load package from CRAN

```{r eval=FALSE}
install.packages("rplos")
```

```{r}
library('rplos')
```

### Search across PLoS papers in various sections of papers

`searchplos` is a general search, and in this case searches for the term
**Helianthus** and returns the DOI's of matching papers

```{r searchplos1}
searchplos(q = "Helianthus", fl = "id", limit = 5)
```

Get only full article DOIs

```{r searchplos2}
searchplos(q = "*:*", fl = 'id', fq = 'doc_type:full', start = 0, limit = 5)
```

Get DOIs for only PLoS One articles

```{r searchplos3}
searchplos(q = "*:*", fl = 'id', fq = 'journal_key:PLoSONE', 
           start = 0, limit = 5)
```

Get DOIs for full article in PLoS One

```{r searchplos4}
searchplos(q = "*:*", fl = 'id',
   fq = list('journal_key:PLoSONE', 'doc_type:full'),
   start = 0, limit = 5)
```

Search for many terms

```{r searchplos5}
q <- c('ecology','evolution','science')
lapply(q, function(x) searchplos(x, limit = 2))
```

### Search on specific sections

A suite of functions were created as light wrappers around `searchplos` as 
a shorthand to search specific sections of a paper.

* `plosauthor` searchers in authors
* `plosabstract` searches in abstracts
* `plostitle` searches in titles
* `plosfigtabcaps` searches in figure and table captions
* `plossubject` searches in subject areas

`plosauthor` searches across authors, and in this case returns the authors of 
the matching papers. the fl parameter determines what is returned

```{r plosauthor}
plosauthor(q = "Eisen", fl = "author", limit = 5)
```

`plosabstract` searches across abstracts, and in this case returns the id and 
title of the matching papers

```{r plosabstract}
plosabstract(q = 'drosophila', fl = 'id,title', limit = 5)
```

`plostitle` searches across titles, and in this case returns the title and 
journal of the matching papers

```{r plostitle}
plostitle(q = 'drosophila', fl = 'title,journal', limit = 5)
```

### Search terms & visualize results as a histogram OR as a plot through time

`plosword` allows you to search for 1 to K words and visualize the results
as a histogram, comparing number of matching papers for each word

```{r plosword1}
out <- plosword(list("monkey", "Helianthus", "sunflower", "protein", "whale"),
    vis = "TRUE")
out$table
```

```{r plosword1plot, fig.width=6, fig.height=4}
out$plot
```

You can also pass in curl options, in this case get verbose information on the 
curl call.

```{r plosword2}
plosword('Helianthus', callopts = list(verbose = TRUE))
```

### Visualize terms

`plot_throughtime` allows you to search for up to 2 words and visualize the 
results as a line plot through time, comparing number of articles matching 
through time. Visualize with the ggplot2 package, only up to two terms for now.

```{r throughtime1, fig.width=6, fig.height=4}
library("ggplot2")
plot_throughtime(terms = "phylogeny", limit = 200) + 
  geom_line(size = 2, color = 'black')
```

### More

See the _Faceted and highlighted searches_ and _Full text_ vignettes for 
more `rplos` help.
