R: Find External Resource References

find_external_resources {rmarkdown} | R Documentation

## Find External Resource References

### Description

Given an R Markdown document or HTML file, attempt to determine the set of additional files needed in order to render and display the document.

### Usage

    find_external_resources(input_file, encoding = getOption("encoding"))

### Arguments

`input_file` | path to the R Markdown document or HTML file to process
`encoding` | the encoding of the document

### Details

This routine applies heuristics in order to scan a document for possible resource references.

In R Markdown documents, it looks for references to files implicitly referenced in Markdown (e.g. `![alt](img.png)`), in the document's YAML header, in raw HTML chunks, and as quoted strings in R code chunks (e.g. `read.csv("data.csv")`).

Resources specified explicitly in the YAML header for R Markdown documents are also returned. To specify resources in YAML, use the `resource_files` key:

    ---
    title: My Document
    author: My Name
    resource_files:
     - data/mydata.csv
     - images/figure.png
    ---

Each item in the `resource_files` list can refer to:

1. A single file, such as `images/figure.png`, or

2. A directory, such as `resources/data`, in which case all of the directory's content will be recursively included, or

3. A wildcard pattern, such as `data/*.csv`, in which case all of the files matching the pattern will be included. No recursion is done in this case.

In HTML files (and raw HTML chunks in R Markdown documents), this routine searches for resources specified in common tag attributes, such as `<img src="...">`, `<link href="...">`, etc.

In all cases, only resources that exist on disk and are contained in the document's directory (or a child thereof) are returned.

### Value

A data frame with the following columns:

path

  The relative path from the document to the resource

explicit

  Whether the resource was specified explicitly (`TRUE`) or discovered implicitly (`FALSE`)

web

  Whether the resource is needed to display a Web page rendered from the document

[Package rmarkdown version 1.6 Index]