在 kable 单元格中添加箭头或图形？

Question

是否可以在带有 pdf_output 的 kable 单元格中添加向上或向下箭头？有没有人幸运地将任何特殊数字添加到 kable 单元中？

我的标题：

---
title: "markdownTest"
header-includes:
- \usepackage{booktabs}
- \usepackage{longtable}
- \usepackage{array}
- \usepackage{multirow}
- \usepackage{wrapfig}
- \usepackage{float}
- \usepackage{colortbl}
- \usepackage{pdflscape}
- \usepackage{tabu}
- \usepackage{threeparttable}
- \usepackage{threeparttablex}
- \usepackage[normalem]{ulem}
- \usepackage{makecell}
- \usepackage{xcolor}
- \usepackage{fontspec}
- \setmainfont{Calibri}
output: 
  pdf_document:
    latex_engine: xelatex
---

Answer 1

您可以运行以下语句：

---
title: "kable arrow"
author: "Alessio Benedetti"
date: "17/11/2019"
output: html_document
---

```{r}
library(knitr)
df <- data.frame(
  stock = c('Apple','Amazon','Microsoft','Tesla'),
  value = c(300,200,150,250),
  difference = c(50,-10,20,-15)
)
df$trend <- ifelse(df$difference >0,
                   '![](https://www.picgifs.com/glitter-gifs/a/arrows/picgifs-arrows-110130.gif)',
                   '![](https://www.picgifs.com/glitter-gifs/a/arrows/picgifs-arrows-30184.gif)'
                  )

kable(df)
```

编辑：要在 pdf 中编织，您需要使用 png 文件（例如：https://images.app.goo.gl/1Qt85stUQggdPRwx7）：

---
title: "kable arrow"
author: "Alessio Benedetti"
date: "17/11/2019"
output:
  pdf_document: default
  html_document: default
---

```{r}
library(knitr)
df <- data.frame(
  stock = c('Apple','Amazon','Microsoft','Tesla'),
  value = c(300,200,150,250),
  difference = c(50,-10,20,-15)
)
df$trend <- ifelse(df$difference >0,
                   '![](arrow_up.png)',
                   '![](arrow_down.png)'
                  )

kable(df)
```