由rmarkdown生成的pdf文档中表格的标题

如何获取由rmarkdown生成的pdf_document中的表格浮动标题?

How can I get captions on my table floats in pdf_document generated by rmarkdown?

使用

output:
  pdf_document:
    fig_caption: true

和

```{r, fig.cap='a caption'} 
myplot 
```

生成带有myplot和指定标题的浮动图形.

Generates a floating figure with myplot and the caption specified.

如何使用xtable生成的表实现相同的目的?

How do I achieve the same thing with tables generated by xtable?

```{r, results='asis', fig.cap='table caption'}
    print(xtable(table), comment = FALSE)
```

我尝试在print.xtable中使用float.environment ='figure'，但无济于事.

I have tried using floating.environment = 'figure' in print.xtable, but to no avail.