【发布时间】：2017-06-17 04:44:03
【问题描述】：
为了测试，请上传一个1+列的csv文件，可以在应用中转换为日期。
我的应用会根据所选日期列动态生成日期范围输入 (input$daterange)。我想验证每个 input$daterange 从 1 到 n（dt$datecols 的长度），以确保用户不会选择早于最旧日期的 start 日期和晚于最新日期的 end 日期相应列中的日期。我在observeEvent 上使用lapply 来做到这一点。
为了便于调试，我将input$daterange(i) 的值传递给反应值dt$daterange(i) 并将dt$daterange1（第一个日期范围的值）打印到渲染的控制台以检查它是否小于或大于@对应日期列的 987654332@ 和 max，就像我在 lapply 函数中所做的那样。假设检查结果为FALSE 时，lappy 函数将显示一条错误消息，警告用户start 或end 日期无效，但不起作用。请在下面找到我的代码，请查看 cmets 以了解问题的解释。
library("shiny")
library("DT") # Datatable
library("rsconnect") # deploy to shinyapps.io
library("shinyjs") # use toggle button from shinyJS pacakage
library("stats")
library("zoo") # to use as.Date() on numeric value
ui <- fluidPage(
fluidRow(
column(4,
# file upload div
fileInput("file", "Choose a file",
accept=c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv"
)),
# show ui for upload file control
uiOutput("ui")
),
column(4,
# no choices before a file uploaded
uiOutput("columnscontrol")
)
),
hr(),
fluidRow(
column(4,
uiOutput("datecolscontrol")),
column(6,
uiOutput("daterangescontrol"))
),
hr(),
dataTableOutput("datatbl"),
# print console for debugging (delete after completion)
verbatimTextOutput("print_con")
) #end of fluidPage (ui)
# server
server <- function(input, output, session) {
#########################################################
# upload & datatable output
#########################################################
# create dataset reactive objects
dt <- reactiveValues()
# reset all uis upon new file upload
observeEvent(input$file, {
# reset reactive values
dt$data = NULL
dt$df = NULL
dt$cols = NULL
dt$rows = NULL
dt$summary = NULL
dt$colchoices = NULL
dt$datecols = NULL
# remove columns div and datecols div when a new file uploaded
removeUI(selector = "div#columns_div")
removeUI(selector = "div#datecols_div")
# remove all <div> elements indside <div>#daterangescontrol:
removeUI(selector = "div#daterangescontrol div")
# generate upload file control ui once file uploaded
output$ui <- renderUI({
actionButton("readF", "Update")
})
})
# when read file button pressed:
observeEvent (input$readF, {
# store data to dt$data
file <- input$file
dt$data <- read.csv(file$datapath, header = TRUE)
# render columnscontrol
output$columnscontrol <- renderUI({
# get the col names of the dataset and assign them to a list
dt$colchoices <- mapply(list, names(dt$data))
# render column group checkbox ui after loading the data
# tags#div has the advantage that you can give it an id to make it easier to reference or remove it later on
tags$div(id = "columns_div",
checkboxGroupInput("columns", "", choices = NULL, selected = NULL))
})
# render div containing #datecols under datecolscontrol
output$datecolscontrol <- renderUI({
tags$div(id = "datecols_div",
selectInput("datecols", "Filter data by dates):", choices = NULL, multiple = TRUE, selected = NULL))
})
})
# update columns choices when dt$choices is ready
observeEvent(dt$colchoices, {
updateCheckboxGroupInput(session, "columns", "Select Columns:", choices = dt$colchoices, selected = dt$colchoices)
})
# the other reactivity on dt$cols is input$file (when new file uploaded, dt$data and dt$cols set to NULL)
# so that the following line set apart the reactivity of input$columns on dt$cols
observeEvent(input$columns, {
dt$cols <- input$columns
dt$df <- dt$data[dt$cols]
}, ignoreNULL = FALSE)
# upon any change of dt$df
observeEvent(dt$df, {
f <- dt$df
# render output$datatbl
output$datatbl <- DT::renderDataTable(
f, rownames = FALSE,
filter = 'top',
options = list(autoWidth = TRUE)
)
# update datecols choices with those columns can be converted to Date only:
dt$date_ok = sapply(f, function(x) !all(is.na(as.Date(as.character(x), format = "%Y-%m-%d"))))
dt$datecolchoices = colnames(f[dt$date_ok])
updateSelectInput(session, "datecols", "Filter data by dates:", choices = dt$datecolchoices, selected = NULL)
}, ignoreNULL = FALSE)
# whenver columns convertable to date updated to choices of input$datecols, convert the columns to Date in the dataset
observeEvent(dt$datecolchoices, {
dt$df[dt$date_ok] = lapply(dt$df[dt$date_ok], function(x) as.Date(as.character(x)))
})
# generate daterange uis per selected input$datecols
observeEvent(input$datecols, {
dt$datecols = input$datecols
dt$datecols_len = length(dt$datecols)
# render daterange ui(s) per selected datecols
output$daterangescontrol <- renderUI({
# when input$datecols is NULL, no daterange ui
if ( is.null(input$datecols) ) { return(NULL) }
# otherwise
else {
D = dt$df[dt$rows, dt$cols]
output = tagList()
for (i in 1:dt$datecols_len) {
output[[i]]= tagList()
output[[i]][[1]] = tags$div(id = paste("dateranges_div", i, sep = "_"),
dateRangeInput(paste0("daterange", i),
paste("Date range of", dt$datecols[[i]]),
start = min(D[[dt$datecols[[i]]]]),
end = max(D[[dt$datecols[[i]]]])))
}
# return output tagList() with ui elements
output
}
}) # end of renderUI
}, ignoreNULL = FALSE)
# loop observeEvent to check whether each input$daterange is valid:
#### why I can't just call lapply() without observe() as suggested in this post:
#### https://stackoverflow.com/questions/40038749/r-shiny-how-to-write-loop-for-observeevent
observe({
lapply( X = 1:dt$datecols_len,
FUN = function(i) {
observeEvent(input[[paste0("daterange", i)]], {
# update reactive values to test whether this loop is working
dt[[paste0("range",i)]] = input[[paste0("daterange", i)]]
range = dt[[paste0("range",i)]]
req(range)
#########################################
## CODE BLOCK WITH PROBLEM!!!
#########################################
# Why the following doesn't work, when I pick a date earlier than the oldest date
# no error message shows!
shiny::validate(
need( range[[1]] >= min(dt$df[[dt$datecols[[i]]]]), "The start date cannot be earlier than the oldest date!"),
need( range[[2]] <= max(dt$df[[dt$datecols[[i]]]]), "The end date cannot be later than the latest date!")
)
})
}
) # end of lapply
})
# rows displayed in input$datatbl (the rendered data table)
observeEvent( input$datatbl_rows_all, {
dt$rows <- input$datatbl_rows_all
})
#########################################################
# print console
#########################################################
output$print_con <- renderPrint({
req(input$daterange1)
list(
# to verify whether the observeEvent loop is working for input validation
# I used dt$range1 to check the first (input$daterange1) against the date range of the corresponding column of the dataset.
# It's supposed that when the check result is FALSE (either by selecting a start date earlier than the oldest date or selecting an end date later than the latest date),
# the code block with problem shall prompt an error message to warn the user
min(dt$range1) >= min(dt$df[[dt$datecols[[1]]]]),
max(dt$range1) <= max(dt$df[[dt$datecols[[1]]]])
)
})
} # end of shiny server function
shinyApp(ui = ui, server = server)
【问题讨论】：
-
请按照有关创建minimal reproducible example 的提示将您的示例简化为说明问题的基本部分。
-
为什么不对日期列表进行排序？您只需比较
[1]st 和[n]th 元素，而不是[i]元素。