在 R Shiny 的 checkboxGroupInput 中列出所有变量（列名）

Question

我正在编写一个 R 闪亮的应用程序。我面临很多麻烦，尤其是 checkboxGroupInput 函数。我希望我能够创建一个动态列表，该列表将自动列出除名为source_file 的数据集的第一列source_file$Date 之外的所有列，我对此并不完全确定。非常感谢您能提供的任何帮助！

source_file 的样本数据集如下所示：

Date	Index 1	Index 2	Index 3	Index 4	Index 5
2016-01-01	+5%	-2%	+5%	+10%	+12%
2016-01-08	+3%	+13%	-8%	-3%	+10%
2016-01-15	+2%	+11%	-3%	+4%	-15%

最终目标是希望 checkboxGroupInput 函数能够自动读取从第二列开始的所有列（忽略日期）。在这种情况下，复选框将加载 5 个选项，索引 1 到索引 5。它应该是可复制的，以便它可以根据指定的数据加载任意数量的索引。我尝试对每个单独的索引进行硬编码，但这绝对是违反直觉的，而且非常令人沮丧。

tabPanel("Target Volatility Portfolio",
                         sidebarPanel(
                           tags$h3("Find an optimised portfolio to achieve maximum return for a given level of risk/volatility"),
                           tags$h4("Input:"),
                           checkboxGroupInput("portfolio_selection",
                                              "Select Number of Indexes for Portfolio",
                                              choices = list(#####please send help here#####)

编辑：如果您能帮我解决这个问题，将不胜感激。

我想以这种格式将来自复选框的输出引用到我的 global.R 中。基本上，我想使用选定的变量来绘制图表。选择 2 个变量将导致绘制与 2 个变量相关的图形，而选择 10 个变量将创建包含所有 10 个变量的图。 （我基本上是在绘制 x 股票数量的有效市场边界，其中 x 是所选变量的数量。它有点难以解释，但我希望附上代码可以为您提供一些见解）哈希线是我需要的帮助定影。谢谢！

plot_emf = function(n_points, target_vol, portfolio_selection)
{
  first <- portfolio_selection[1]
  last <- portfolio_selection[length(portfolio_selection)]
  
  #######asset_returns = source_file[first:last]########

  # Extract necessary parameters
  n_assets = ncol(asset_returns)
  n_obs = nrow(asset_returns)
  n_years = n_obs / 52
  
  # Initialize containers for holding return and vol simulations
  return_vector = c()
  vol_vector = c()
  sharpe_vector = c()
  
  for (i in 1:n_points)
  {
  # Generate random weights for n assets from uniform(0,1)
  asset_weights = runif(n_assets, min = 0, max = 1)
  normalization_ratio = sum(asset_weights)
  # Asset weights need to add up to 100%
   
  asset_weights = asset_weights / normalization_ratio
  # print(asset_weights)
  # print(asset_returns)
  
  # Generate the portfolio return vector using these weights
  random_portfolio_returns = emf_portfolio_returns(
    asset_weights,
    asset_returns)
  # print(random_portfolio_returns)
  # plot_returns_histogram(random_portfolio_returns$portfolio_returns)
  
  cumulative_return = calculate_cumulative_return(random_portfolio_returns$portfolio_returns)
  annualized_return = 100*((1 + cumulative_return/100)^(1/n_years) - 1)
  annualized_vol = sd(random_portfolio_returns$portfolio_returns)*(52^0.5)
  sharpe = annualized_return / annualized_vol
  
  return_vector = append(return_vector, annualized_return)
  vol_vector = append(vol_vector, annualized_vol)
  sharpe_vector = append(sharpe_vector, sharpe)
  
  #print(paste("Asset weights:",asset_weights))
  #print(paste("Anualized return:",annualized_return))
  #print(paste("Annualized vol:",annualized_vol))
  }
  
  g = ggplot(data = data.frame(vol_vector, return_vector, sharpe_vector),
             aes(x = vol_vector, y = return_vector, color = sharpe_vector)) +
    scale_color_gradient(low = "red", high = "blue", name = "Sharpe Ratio\n(Return/Risk)") + 
    ggtitle("Efficient Market Frontier") +
    xlab("Annualized Vol (%)") +
    ylab("Annualized Return (%)") + 
    theme(plot.title = element_text(hjust=0.5)) + geom_vline(xintercept=target_vol) +
    geom_point()
  print(g) 
} 

Answer 1

您可以尝试使用colnames() 提取新选项，然后将checkboxGroupInput 更新为updateCheckboxGroupInput()：

server <- function(input, output, session) {
  
  # Read the data once per session - this step might be better to
  # put in a `global.R` file
  source_file <- read.csv("source_file.csv")
  
  # Column names we want to show - all except `Date`
  opts <- setdiff(colnames(source_file), "Date") 
 
  # Update your checkboxGroupInput:
  updateCheckboxGroupInput(
    session, "portfolio_selection", choices = opts
  )
   
  # Rest of app after this point  --------------------------------------

}