Improve the accesibility of rmarkdown created html-documents

Publishing Your Results
11

@ChristianL,

this is an example of a knitr plot hook that supports only the arguments caption and alt.
All other arguments you would like to use you should include yourself.
For my convenience I also used nocaption and noalt but because these are not recognized they have the same meaning as not specifying caption resp. alt .

---
author: "C Lindell"
title: "my title"
date: '2020-06-24'
output:
  html_document:
    toc: yes
    toc_float: yes
    keep_md: yes
---


```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning = FALSE, message = FALSE)

knitr::knit_hooks$set(plot = function(x,options) {
      base = knitr::opts_knit$get('base.url')
      if (is.null(base)) base = ''
      alt = ifelse (is.null(options$alt),"",options$alt)
      cap = ifelse (is.null(options$caption),"",options$caption)
      if (alt != ""){
        sprintf('![%s](%s%s "%s")', cap, base, x, alt)
      } else {
        sprintf('![%s](%s%s)', cap, base, x)  
        }
  })

```

# Diagrams and pictures

How do I provide a generated diagram with a "alt text"-tag to make it readable for the vision impaired?

```{r}
library(ggplot2)
```
### plot with caption and alt_text
```{r plot1,caption='nice plot',alt='my alt_text'}
ggplot(cars, aes(speed, dist)) +
  geom_line()
```

### plot without caption and with alt_text
```{r plot2,nocaption='nice plot',alt='my alt_text'}
ggplot(cars, aes(speed, dist)) +
  geom_line()
```

### plot with caption and without alt_text
```{r plot3,caption='nice plot',noalt='my alt_text'}
ggplot(cars, aes(speed, dist)) +
  geom_line()
```
5 Likes