这个问题困扰一天两夜，记录一下
解决办法参考s1
问题：
Shiny 接收多个文件，每个文件生成一张图片，结束。最后将地址通过 params 传给 Rmarkdown(Rmd)，生成报告。这里面需要在Rmd中进行遍历，但是在for loop中遍历 使用knitr::include_graphics() 无法在Rmd展示图片。Demo Code:
Shiny
library(shiny)
shinyApp(
ui = fluidPage(
textInput("s1", "Description 1", "image1.png"),
textInput("s2", "Description 2", "image2.png"),
downloadButton("report", "Generate report")
),
server = function(input, output) {
output$report <- downloadHandler(
filename = "report.html",
content = function(file) {
tempReport <- file.path(tempdir(), "report.Rmd")
file.copy("volcano2.Rmd", tempReport, overwrite = TRUE)
params <- list(tag = c(input$s1, input$2"))
rmarkdown::render(tempReport, output_file = file,
params = params,
envir = new.env(parent = globalenv())
)
}
)
}
)
为了突出主要问题，这里直接把已经存在tempdir()的图片名作为 params。
volcano2.Rmd
---
title: xxxx
author: `r knitr::opts_chunk$set(echo = FALSE, out.width="30%")``r knitr::include_graphics(paste("G:\\Project\\workspace","www\\xxx.jpg",sep="\\"))`
date: `r format(Sys.Date(),'%Y-%m-%d')`
runtime: "static"
params:
tag: NA
output:
html_document:
toc: no
toc_float: yes
keep_md: true
theme: flatly
number_sections: false
---
``` {r}
knitr::opts_chunk$set(echo = FALSE, message = TRUE, warning = TRUE) ``` # Rmd的R 代码块于md语法的代码一样，为了避免歧义这样写
# xxxxx
1234
### {.tabset .tabset-fade .tabset-pills}
```{r, results='asis', out.width='60%', echo=FALSE}
n <- params$tag
for (i in n){
cat("#### " ,i, "\n\n")
a <- paste(tempdir(), i, sep = "\\")
cat(knitr::include_graphics(a))
# knitr::include_graphics(a)
cat('\n\n')
} ```
### {-}
cat(knitr::include_graphics(a)) 不出图的原因参见yihui : include_graphics() has to be used in top-level R expressions. 即无法在循环内使用，因此解决办法有：
1. Rmd插入图片，但是无法改样式
```{r, results='asis', out.width='60%', echo=FALSE}
n <- params$tag
for (i in n){
cat("#### " ,i, "\n\n")
a <- paste(tempdir(), i, sep = "\\")
aaa #见下面
cat('\n\n')
} ```
2.HTML插入图片，可以改样式，推荐！！！
```{r, results='asis', out.width='60%', echo=FALSE}
n <- params$tag
for (i in n){
cat("#### " ,i, "\n\n")
a <- paste(tempdir(), i, sep = "\\")
cat("
")
cat('\n\n')
} ```
aaa : cat("[图片上传失败...(image-3b0c65-1598935814989)]")