我正在学习 Shiny + flexdashboard。我阅读了有关我收到的错误声明的 stackoverflow 帖子，但我仍然无法弄清楚我的具体情况（可能是因为我是这方面的初学者）。
下面是产生错误的代码。
如果在最后一行代码而不是 col=input$plot_color) 我使用 col=”brown”，则相同的代码运行良好）
我正在用头撞墙，试图弄清楚为什么 col = input$line_color 在 Geyser 页上的 Geyser 图中起作用，但 col=input$plot_color 在 Pg 测试图页上不起作用
---
title: "Old Faithful Eruptions"
output: flexdashboard::flex_dashboard
runtime: shiny
---
```{r global, include=FALSE}
# load data in 'global' chunk so it can be shared by all users of the dashboard
library(datasets)
library(readr)
data(faithful)
```
Page Geyser
=====================================
Column {.sidebar data-width=300}
----------------------------------------------------------------------
Example from http://rmarkdown.rstudio.com/flexdashboard/shiny.html
Waiting time between eruptions and the duration of the eruption for the
Old Faithful geyser in Yellowstone National Park, Wyoming, USA.
```{r selectInput}
# Comment here
color.choices=c("blue", "red", "black")
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20)
selectInput("line_color", label = "Coor of line:",
choices = color.choices, selected = "red")
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
```
Column {data-width=650}
-----------------------------------------------------------------------
### Geyser Eruption Duration Hist
```{r renderPlot_Geyser}
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser Eruption Duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = input$line_color)
})
```
Pg Test plots
=====================================
Column {.sidebar data-width=500}
----------------------------------------------------------------------
```{r selectInput_page_2}
# Comment here
color.choices2=c("blue", "red", "brown", "green")
selectInput("multiplier_for_x", label = "Y= x*:",
choices = c(1, 2, 3, 5), selected = 2)
selectInput("plot_color", label = "Color of plot:",
choices = color.choices2, selected = "brown")
```
Column {data-width=350}
-----------------------------------------------------------------------
### Chart B
```{r chart_b}
plot(1:10,
1:10,
main="Plot in chart B section of code",
sub="Y= x*:",
col=input$plot_color)
```