在我的flexdashboard闪亮应用程序中，我使用的selectizeInput()具有三个选项：“英语”，“西班牙语”和“其他”。在我的玩具数据集中，没有观察到变量lang带有值“ other”。因此，在输入栏中选择仅“其他”时，R返回评估错误：
需要TRUE / FALSE的缺失值。
这是由“页面1”部分中的以下几行引起的：
filter(if(is.null(input$foo)) (new==1) else (lang %in% input$foo)) %>%
当数据集中没有采用输入值的观测值时，显示空白图的正确方法是什么？
---
title: "test"
output:
flexdashboard::flex_dashboard:
theme: bootstrap
runtime: shiny
---
```{r setup, include=FALSE}
library(flexdashboard)
library(tidyverse)
library(tibbletime)
library(dygraphs)
library(magrittr)
library(xts)
```
```{r global, include=FALSE}
# generate data
set.seed(1)
dat <- data.frame(date = seq(as.Date("2018-01-01"),
as.Date("2018-06-30"),
"days"),
sex = sample(c("male", "female"), 181, replace=TRUE),
lang = sample(c("english", "spanish"), 181, replace=TRUE),
age = sample(20:35, 181, replace=TRUE))
dat <- sample_n(dat, 80)
```
Sidebar {.sidebar}
=====================================
```{r}
selectizeInput(
'foo', label = NULL,
choices = c("english", "spanish", "other"),
multiple = TRUE
)
```
Page 1
=====================================
```{r}
# all
totals <- reactive({
dat %>%
mutate(new = 1) %>%
arrange(date) %>%
filter(if(is.null(input$foo)) (new==1) else (lang %in% input$foo)) %>%
# time series analysis
tibbletime::as_tbl_time(index = date) %>% # convert to tibble time object
select(date, new) %>%
tibbletime::collapse_by("1 week", side = "start", clean = TRUE) %>%
group_by(date) %>%
mutate(total = sum(new, na.rm = TRUE)) %>%
distinct(date, .keep_all = TRUE) %>%
ungroup() %>%
# expand matrix to include weeks without data
complete(
date = seq(date[1], date[length(date)], by = "1 week"),
fill = list(total = 0)
)
})
# convert to xts
totals_ <- reactive({
totals <- totals()
xts(totals, order.by = totals$date)
})
# plot
renderDygraph({
totals_ <- totals_()
dygraph(totals_[, "total"]) %>%
dyRangeSelector() %>%
dyOptions(useDataTimezone = FALSE,
stepPlot = TRUE,
drawGrid = FALSE,
fillGraph = TRUE)
})
```