Bookdown preview_chapter

Question

我似乎无法让preview_chapter处理我的r bookdown项目。这是我的_bookdown.yml文件：

book_filename: "thesis"
delete_merged_file: true
output_dir: "docs"
new_session: yes 

rmd_files: # defines the .Rmd files to be included for each output format
  html: ["index.Rmd", "02-methodology.Rmd", "03-results.Rmd", "99_references.Rmd"]

当我使用：

bookdown::render_book("index.Rmd", bookdown::'gitbook')

整本书都能正确编译。但如果我尝试构建一个章节，如下所示：

 bookdown::preview_chapter("03-results.Rmd", bookdown::'gitbook')

我得到了：

Error in files2[[format]] : 
  attempt to select less than one element in get1index

我是否使用了错误的语法？

Answer 1

bookdown::'gitbook'应为'bookdown::gitbook'。