有条件地在R Markdown中显示文本块

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我正在使用knitr解析R Markdown文档.有没有一种方法可以根据我传递给knitr的环境中的变量在R Markdown中有条件地显示文本块?

I am using knitr to parse an R Markdown document . Is there a way to conditionally display a block of text in R Markdown depending on a variable in the environment I pass into knitr?

例如，类似:

`r if(show.text) {` la la la `r }`

如果show.text为true，则将在结果文档中打印"la la la".

Would print "la la la" in the resulting doc if show.text is true.

推荐答案

您需要一个完整的R表达式，因此您不能像显示的那样将其分成多个块，但是如果块的结果是文本字符串，则它将被原样包含(不带引号)，因此您应该可以执行以下操作:

You need a complete R expression, so you cannot break it into multiple blocks like you show, but if the results of a block are a text string then it will be included as is (without quotes), so you should be able to do something like:

`r if(show.text){"la la la"}`

，并且仅当show.text为TRUE时，它才会包含文本.

and it will include the text if and only if show.text is TRUE.