RMarkdown V2 Shiny Document和dplyr

Question

我正在尝试使用dpdownr的rmarkdown v2输入选择来选择要报告的某些列.然后,将在给定nls()函数的公式中使用所选列来确定某些常量C的值.

我的代码如下:

---
title: "Test"
author: "Author"
date: "Wednesday, June 18, 2014"
output: html_document
runtime: shiny
---

```{r, echo=TRUE}
require(dplyr)
#Some sample random data in a data.frame:
test=data.frame(A=runif(n=10),V=runif(n=10),N=runif(n=10))

#Input box to choose desired column
inputPanel(
  selectInput('sample.choice', label = 'Choose Columns',
              choices = c('V Sample'='V',
                          'N Sample'='N'),
              selected='N')
)

#Make a reactive data.frame to be used with the nls function
test2=reactive(test%.%select(A,input$sample.choice))

#Display the data.frame
renderDataTable(test2())

#Use nls solver to determine a constant with a given formula:
c.fit=reactive(nls(A ~ I(C*input$sample.choice),data=test2(),start=list(C=1)))
renderText(summary(c.fit()))
```

Error: non-numeric argument to mathematical function在调用renderDataTable和renderText之后,我得到了输出.

任何人都可以帮我弄清楚这里有什么问题吗？

更新

基于@wch注释,我修复了dplyr select函数.我也试图调用renderText,但输出summary.nls是类型列表.这不起作用,我需要改为运行renderPrint.请参阅下面的工作代码:

```{r, echo=TRUE}
require(dplyr)
test=data.frame(A=runif(n=10),V=runif(n=10),N=runif(n=10))

inputPanel(
  selectInput('sample.choice', label = 'Choose Columns',
              choices = c('V Sample'='V',
                          'N Sample'='N'),
              selected='N')
)

renderText(input$sample.choice)

test2=reactive(test%.%select(A,matches(input$sample.choice)))

renderDataTable(test2())

renderPrint({
  data=test2()
  formula=paste0('A ~ I(C*',input$sample.choice,')')
  c.fit=nls(formula,data=data,start=list(C=1))
  summary(c.fit)
})

```

Answer 1

我认为问题在于这一行:

test %>% select(A, input$sample.choice)

最终解决这样的事情:

test %>% select(A, "V")

但是dplyr需要这个,因为它使用非标准评估:

test %>% select(A, V)

这是一种可能的解决方法:

test %>% select(A, matches(input$sample.choice))