呈现包含 sparklyr 代码的 R Markdown 文件时失败Rendering an R markdown file containing sparklyr code fails
问题Problem
在 Azure Databricks 环境中安装并配置好 RStudio 之后，启动 RStudio 并单击“编织”按钮以编织一个包含 sparklyr 上下文初始化代码的 Markdown 文件时，呈现失败并出现以下错误：After you install and configure RStudio in the Azure Databricks environment, when you launch RStudio and click the Knit button to knit a Markdown file that contains code to initialize a sparklyr context, rendering fails with the following error:
failed to start sparklyr backend:object 'DATABRICKS_GUID' not found Calls: <Anonymous>… tryCatch -> tryCatchList-> tryCatchOne -> <Anonymous> Execution halted
原因Cause
如果尝试使用类似以下内容的代码在 Markdown 笔记本中初始化 sparklyr 上下文，则 Markdown 页将无法呈现，因为 knitr 进程会生成缺少 'DATABRICKS_GUID' 全局变量的新命名空间。If you try to initialize a sparklyr context in a Markdown notebook with code similar to the following, the Markdown page fails to render because the knitr process spawns a new namespace that is missing the 'DATABRICKS_GUID' global variable.
case library(sparklyr)
sc <- spark_connect(method = "databricks")
解决方案Solution
请使用以下脚本来呈现 Markdown 页，而不是单击 R Markdown 控制台中的“编织”按钮：Instead of rendering the Markdown page by clicking the Knit button in the R Markdown console, use the following script:
rmarkdown::render("your_doc.Rmd")
使用 R 控制台呈现 Markdown 文件，然后就可以在 RStudio“文件”选项卡中访问该文件。Render the Markdown file using the R console, and then you can access the file in the RStudio Files tab.
