在 for 循环中打印 DiagrammeR 对象

Question

在 R Markdown 文档的循环中是否有直接打印 DiagrammeR 对象的方法？我有一个文档，其中为多个模型分别生成了一个回归 table、一个绘图和一个图表，并一起打印。使用 for 循环很容易做到这一点，但是 DiagrammeR 对象不会在循环内打印（即使使用 print(graph).

这样的显式调用也是如此）

这已在其他地方记录（参见：https://github.com/rich-iannone/DiagrammeR/issues/39），但 2015 年建议的解决方案现在似乎不起作用（并且仅限于 html 输出）。

请参阅下面的 Rmd 示例代码。

---
title: "DiagrammeR loop test"
author: ""
date: "11/20/2020"
output: pdf_document
---


# Some header
Printing a single flowchart works fine in knitr using the DiagrammeR package. 

```{r figure_1, out.width = "15%", echo = FALSE, fig.align = 'center', fig.cap = "Flowchart 1: This prints fine."}

DiagrammeR::grViz(" 
      digraph test {

        node [shape = circle] 
          A; B

        A -> B

      }
        ")

```

Flowchart 2 which is inside a loop, however, does not print 


```{r figure_2, out.width = "15%", echo = FALSE, fig.align = 'center', fig.cap = "Flowchart 2: These two diagrams do not print even with an explicit print command."}

for (i in 1:2){
  
graph <- DiagrammeR::grViz(" 
      digraph test {

        node [shape = circle] 
          A; B

        A -> B

      }
        ")

print(graph)  
}

Answer 1

修复方法如下：

# Create an empty list to save the htmlwidgets
plot_list <- htmltools::tagList()

for (i in 1:2){
  
graph <- DiagrammeR::grViz(" 
      digraph test {

        node [shape = circle] 
          A; B

        A -> B

      }
        ")

# Store the htmlwidget inside this list
plot_list[[i]] <- graph 
}

#Print this list
plot_list

在 for 循环中打印 DiagrammeR 对象

Print DiagrammeR object inside for-loop

r

diagrammer