RMarkdown：如果没有数据，则不在文档中包含表格交叉引用

Question

有时，数据子集不包含任何记录，因此不应生成表。当我想打印满足特定命令的表格时，可能会发生这种情况。 Word 文档对空表的引用是“Table ??”默认情况下。但是，我不想打印此参考资料。

例如markdown文档：

---
title: "Dont show Table reference if no data"
date: "2024-01-09"
---

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

## R Markdown

Show this table reference if data exists

## No Data

Find species V in the iris dataset.

```{r iris-v}
iris_v <- iris %>% filter(Species == "V") 
```
`r nrow(iris_v)` records of species V exist for iris. 

Don't show this table reference because there is no data - avoid **Table ??** being printed.

**Table \@ref(tab:ft-B)**

```{r ft-B}
#Only print flextable if data exists 
if(nrow(iris_v) > 0){
  flextable::flextable(head(iris_v, 5))
}
```

通过

呈现为Word文档

rmarkdown::render(
  input = paste0("dont_show_if_no_reference.Rmd"),
  output_format = bookdown::word_document2(
    number_sections = FALSE,     #sections are numbered in template to match header style.
    global_numbering = TRUE,
    toc = FALSE,  #Grading does not have TOC
    toc_depth = 4, # DEFAULT Depth of headers to include in table of contents
    df_print = "kable",
    fig_width = 7, # inches
    fig_height = 6, # inches
    fig_caption = TRUE,
    keep_md = FALSE # verbose   #keep the markdown file from knitting

  ),
  clean = TRUE,
  quiet = FALSE
)

word文档如下所示：

我认为有条件地在 Rmd 文档中包含此 r 代码可以解决问题：

`r if(nrow(iris) > 0) "**Table \\\@ref(tab:ft-A)**"`

但我收到此错误：

! Failed to parse the inline R code: "**Table \\\@ref(tab:ft-A)**"
Reason: '\@' is an unrecognized escape in character string starting "**Table \\\@"

Answer 1

据我所知，主要原因是缺少flextable的标题（以及转义反斜杠的数量）。

以下是我的例子：

```{r iris-v}
iris_v <- iris %>% filter(Species == "V") 
```
`r nrow(iris_v)` records of species V exist for iris. 

`r if(nrow(iris_v) > 0) "**Table \\@ref(tab:ft-V)**"`

```{r ft-V}
# Only print flextable if data exists 
if(nrow(iris_v) > 0){
  flextable::flextable(head(iris_v, 5)) %>% 
    flextable::set_caption(caption = "")
}
```