knitr - 数字幻灯片

Question

对于产生许多图形的

knitr

块，我想要一个幻灯片而不是一长串图像，类似于this。

我遇到了

fig.show='animate'

，这还可以，但速度很慢，而且是一部电影而不是单个图像。

下面的解决方案也可以，但我想要一些适用于

self_contained: yes

的解决方案，这样我就不必单独保留图像。我对html了解不够，但“自包含”图像只是源代码中的长字符串，我不知道如何使用。

还感觉构建图像的文件路径有点hacky。

--- R 降价

---
output:
  html_document:
    self_contained: no
---

```{r, fig.show='animate'}
tmp <- lapply(names(mtcars)[-1L], function(x) {
  plot(reformulate(x, 'mpg'), mtcars, main = 'fig.show=\'animate\'')
})
```

```{r, fig.show='hide'}
oo <- knitr::opts_current$get()
tmp <- lapply(names(mtcars)[-1L], function(x) {
  plot(reformulate(x, 'mpg'), mtcars, main = 'slideshow')
})
```

```{r, echo=FALSE}
slideshow <- function(img, caption = basename(img)) {
  # cat(slideshow(c('img1.jpg', 'img2.jpg')))

  p <- function(...) {
    paste0(..., collapse = '')
  }

  slide <- function(img, caption = '') {
    caption <- rep_len(caption, length(img))
    single <- '
    <div class="mySlides">
      <div class="numbertext">%s / %s</div>
      <img src="%s" style="width: 100%%">
      <div class="text">%s</div>
    </div>
    '
    sprintf(single, seq_along(img), length(img), img, caption)
  }

  dots <- sprintf('\n<span class="dot" onclick="currentSlide(%s)"></span>',
    seq_along(img)
  )
  
  div <- '
  <div class="slideshow-container">
    %s
    <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
    <a class="next" onclick="plusSlides(1)">&#10095;</a>
  </div>
  <br />
  <div style="text-align: center">
    %s
  </div>
  '
  
  structure(sprintf(div, p(slide(img, caption)), p(dots)), class = 'html')
}

fp <- sprintf('%s-%s.%s', file.path(oo$fig.path, oo$label), seq_along(tmp), oo$dev)
slideshow(fp)
```

<!-- 

https://www.w3schools.com/howto/howto_js_slideshow.asp

-->

<style>
* {box-sizing:border-box}

/* slideshow container */
.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}

/* hide the images by default */
.mySlides {
  display: none;
}

/* next & previous buttons */
.prev, .next {
  cursor: pointer;
  position: absolute;
  bottom: 0%;
  width: auto;
  margin-top: 0px;
  padding: 16px;
  color: #7f7f7f;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
  user-select: none;
}

/* position the "next button" to the right */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* on hover add black background color with transparency */
.prev:hover, .next:hover {
  background-color: rgba(127,127,127,0.8);
  color: white;
}

/* caption text */
.text {
  color: #7f7f7f;
  font-size: 22px;
  padding: 0px 0px;
  position: absolute;
  bottom: -10px;
  width: 100%;
  text-align: center;
}

/* number text (1/3, 2/3, etc) */
.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}

/* dots/bullets/indicators */
.dot {
  cursor: pointer;
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active, .dot:hover {
  background-color: #7f7f7f;
}
</style>

<script>
let slideIndex = 1;
showSlides(slideIndex);

function plusSlides(n) {
  showSlides(slideIndex += n);
}

function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  let i;
  let slides = document.getElementsByClassName("mySlides");
  let dots = document.getElementsByClassName("dot");
  if (n > slides.length) {slideIndex = 1} 
  if (n < 1) {slideIndex = slides.length}
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none"; 
  }
  for (i = 0; i < dots.length; i++) {
    dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex-1].style.display = "block"; 
  dots[slideIndex-1].className += " active";
}
</script>

--- 产生这个

Answer 1

表示图像的长字符串称为base64编码。您可以使用包 base64enc.

从图像生成这样的字符串。

要在 Rmarkdown 文档中包含幻灯片，您可以使用包 swipeR 或包 slickR。下面是一个使用 swipeR 的示例。我在子文件夹“www”中有四个“png”图像。

---
title: "Using 'swipeR' in Rmarkdown"
output: html_document
date: "2023-11-16"
---

```{r setup, include=FALSE}
library(swipeR)
library(htmltools)
library(base64enc)
```

```{r, echo=FALSE}
# base64 encoding of the images
b64_1 <- dataURI(file = "www/img1.png", mime = "image/png")
b64_2 <- dataURI(file = "www/img2.png", mime = "image/png")
b64_3 <- dataURI(file = "www/img3.png", mime = "image/png")
b64_4 <- dataURI(file = "www/img4.png", mime = "image/png")
```

```{r, echo=FALSE}
# carousel
wrapper <- swipeRwrapper(
  tags$img(src = b64_1, style = "width: 400px; margin: auto;"),
  tags$img(src = b64_2, style = "width: 400px; margin: auto;"),
  tags$img(src = b64_3, style = "width: 400px; margin: auto;"),
  tags$img(src = b64_4, style = "width: 400px; margin: auto;")
)
swipeR(wrapper, height = "400px", navigationColor = "navy")
```