Shiny R中的eval（substitute（expr），envir，enclos）错误答案

【问题标题】：Error in eval(substitute(expr), envir, enclos) in Shiny RShiny R中的eval（substitute（expr），envir，enclos）错误
【发布时间】：2015-03-06 16:57:28
【问题描述】：

我在尝试运行我正在构建的 Shiny 应用程序时收到以下错误。错误是：

Listening on http://........
Error in eval(substitute(expr), envir, enclos) : 
  incorrect length (0), expecting: 202

我一直在按照电影浏览器示例应用程序对我的应用程序的基础进行建模。数据通过 CSV 输入，是一个 202 行长的数据帧。

更新
通过调试器运行后，我发现导致错误的实际表达式在 %>% 函数中找到。执行以下两行代码后出现错误：

env[["_lhs"]] <- eval(lhs, parent, parent)
result <- withVisible(eval(quote(`_fseq`(`_lhs`)), env, env))

此时代码中的变量值为：

lhs = 公司
父母 = 环境
env = 环境

显然，代码正在等待我的数据帧，但正在接收一个空集。原因不明。

结束更新

具体问题：我做错了什么以及如何解决？

我的 server.R 文件如下所示：

library(shiny)
library(dplyr)
library(ggvis)

all_dat = read.csv("data/company_data.csv")

shinyServer(function(input, output, session) {

companies <- reactive({
# Filter the clicks, views, opens
clicks <- input$Clicks
pageviews <- input$Pageviews
opens <- input$Opens
engage_value <- input$Engage_Value
viewspermsg <- input$views_per_msg
clickspermsg <- input$clicks_per_msg
openspermsg <- input$opens_per_msg

# Apply Filters
d <- all_dat %>%
  filter(
    Clicks >= clicks,
    Pageviews >= pageviews,
    Opens >= opens,
    Engage_Value >= engage_value,
    views_per_msg >= viewspermsg,
    clicks_per_msg >= clickspermsg,
    opens_per_msg >= openspermsg
    ) %>%
  arrange(Clicks)

# Optional: filter by Dive
if (input$Dive != "All") {
  size <- paste0("%", input$Dive, "%")
  d <- d %>% filter(Dive %like% dive)
}
# Optional: filter by Dive Family
if (input$Family != "All") {
  family <- paste0("%", input$Family, "%")
  d <- d %>% filter(Family %like% family)
}
# Optional: filter by Industry
if (input$Industry != "All") {
  industry <- paste0("%", input$Industry, "%")
  d <- d %>% filter(Industry %like% industry)
}
# Optional: filter by Dive Family
if (input$Size != "All") {
  size <- paste0("%", input$Size, "%")
  d <- d %>% filter(Size %like% size)
}

d <- as.data.frame(d)

d$Has_International <- character(nrow(d))
d$Has_International[d$Oscars == 0] <- "No"
d$Has_International[d$Oscars >= 1] <- "Yes"
#I don't know if I need this.
d
  })

  company_tooltip <- function(x) {
if (is.null(x)) return(NULL)
if (is.null(x$Unnamed..0)) return(NULL)

all_dat <- isolate(companies())
company <- all_dat[all_dat$Unnamed..0 == x$Unnamed..0, ]

paste0("<b>", company$Company, "</b><br>",
  company$Industry, "<br>",
  company$Size, " employees", "<br>",
  company$Company_Type, "<br>",
  round(company$Percent_New, digits=2), " % New Readers"
)
  }

  #reactive labels and graph aspects
  vis <- reactive({
    # Labels for axes
    xvar_name <- names(axis_vars)[axis_vars == input$xvar]
    yvar_name <- names(axis_vars)[axis_vars == input$yvar]

# Normally we could do something like props(x = ~BoxOffice, y = ~Reviews),
# but since the inputs are strings, we need to do a little more work.
xvar <- prop("x", as.symbol(input$xvar))
yvar <- prop("y", as.symbol(input$yvar))

companies %>%
  ggvis(x = xvar, y = yvar) %>%
  layer_points(size := 50, size.hover := 200,
               fillOpacity := 0.2, fillOpacity.hover := 0.5,
               stroke = ~Has_International, key := ~Unnamed..0) %>%
  add_tooltip(company_tooltip, "hover") %>%
  add_axis("x", title = xvar_name) %>%
  add_axis("y", title = yvar_name) %>%
  add_legend("stroke", title = "International Presence", values = c("Yes", "No")) %>%
  scale_nominal("stroke", domain = c("Yes", "No"),
                range = c("orange", "#aaa")) %>%
  set_options(width = 500, height = 500)
  })

  vis %>% bind_shiny("plot1")

})

【问题讨论】：

标签： r shiny shiny-server ggvis

【解决方案1】：

解决方案：在设置过滤器的代码中，引用所有小写的变量名 (input$dive)，而不是最初出现在初始数据框中的大写变量名 (input$Dive) .所以把 input$Dive 改成 input$dive。

错误的方式

# Optional: filter by Dive
if (input$Dive != "All") {
  size <- paste0("%", input$Dive, "%")
  d <- d %>% filter(Dive %like% dive)
}

正确的方法。

# Optional: filter by Dive
if (input$dive != "All") {
  size <- paste0("%", input$dive, "%")
  d <- d %>% filter(Dive %like% dive)
}

【讨论】：