選擇的解決方案添加到此 OP 的末尾
在下面縮短的可重現代碼中，用戶可以通過單擊downloadButton()UI 頂部的 下載輸出資料幀。當下載為 csv 檔案時，如何在表格上方插入一行描述表格的文本？如底部的影像所示。
可重現的代碼：
library(dplyr)
library(DT)
library(shiny)
library(shinyWidgets)
library(tidyverse)
ui <-
fluidPage(fluidRow(
column(width = 8,
h3("Click below to download:"),
downloadButton("sumsDownload","Download",style = "width:20%;"),
h3("Summed Data:"),
DT::dataTableOutput("sums")
)
))
server <- function(input, output, session) {
data <- reactive({
data.frame(
Period = c("2020-01", "2020-02", "2020-03", "2020-01", "2020-02", "2020-03"),
ColA = c(1000.01, 20, 30, 40, 50, 60),
ColB = c(15.06, 25, 35, 45, 55, 65)
)
})
summed_data <- reactive({
data() %>%
group_by(!!sym("Period")) %>%
select("ColA", "ColB") %>% summarise(across(everything(), sum))
})
output$sums <- renderDT({datatable(data = summed_data(),rownames = FALSE)})
output$sumsDownload <- downloadHandler(
filename = function() {paste("sumsDownload","csv",sep=".")},
content = function(file) {write.csv(summed_data(), file,row.names=FALSE)}
)
}
shinyApp(ui, server)
選擇的解決方案：
創建一個反應性資料框df，將summed_data()資料框與一個向量（放置在資料框的頂部df）合并，該向量的表名稱為“Summed Data”，后跟該行中的一系列 NA，然后在downloadHandler(). 下面downloadHandler()的內容也是從 OP 修改的，替換write.csv()為write.table().
df <- reactive({ # `df` modifies `summed_data` for csv download
as.data.frame(
rbind(
c("Summed Data",rep(NA,ncol(summed_data())-1)),
colnames(summed_data()),
matrix(unlist(summed_data(), use.names=FALSE),
nrow = nrow(summed_data()),
)
)
)
})
output$sumsDownload <- downloadHandler(
filename = function() {paste("sumsDownload","csv",sep=".")},
content = function(file){
write.table(
df(),
na = "",
file,
sep = ",", # add this per road_to_quantdom on May/05/22
col.names = FALSE,
row.names = FALSE)
}
)
}
uj5u.com熱心網友回復：
以追加模式打開輸出檔案，寫入標題行，然后寫入 CSV 資料：
f <- file("mtcars.csv", "a")
writeLines("Motor Trend Car Road Tests", f)
write.csv(mtcars, f)
close(f)
head(readLines("mtcars.csv"))
#> [1] "Motor Trend Car Road Tests"
#> [2] "\"\",\"mpg\",\"cyl\",\"disp\",\"hp\",\"drat\",\"wt\",\"qsec\",\"vs\",\"am\",\"gear\",\"carb\""
#> [3] "\"Mazda RX4\",21,6,160,110,3.9,2.62,16.46,0,1,4,4"
#> [4] "\"Mazda RX4 Wag\",21,6,160,110,3.9,2.875,17.02,0,1,4,4"
#> [5] "\"Datsun 710\",22.8,4,108,93,3.85,2.32,18.61,1,1,4,1"
#> [6] "\"Hornet 4 Drive\",21.4,6,258,110,3.08,3.215,19.44,1,0,3,1"
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