Shiny Dashboard Date Slider Input - r

Question

I am new to R and Shiny and have a problem that I have not been able to solve for hours.
I have a dataset from which I display the daily consumption of coffee on a dashboard, which works very well. The plot is a ggplot geom_line chart.
But now I want to be able to change the time period with two sliders.
The sliders I have also managed to do, but the plot does not change when the slider is moved.
I also suspect that I have an error with the date format.
What am I doing wrong?
Thanks for the help
RawData Dataset
library(shiny)
library(dplyr)
library(data.table)
library(ggplot2)
ui <- shinyUI(fluidPage(
# Application title
titlePanel("Coffee consumption"),
# Sidebar with a slider input for the number of bins
sidebarLayout(
sidebarPanel(
sliderInput("DatesMerge",
"Dates:",
min = as.Date("2018-01-22","%Y-%m-%d"),
max = as.Date("2020-04-04","%Y-%m-%d"),
value= c(as.Date("2018-01-22","%Y-%m-%d"),as.Date("2020-04-04","%Y-%m-%d")),
timeFormat="%Y-%m-%d")
),
mainPanel(
plotOutput("plot_daycount"),
tableOutput("structure"),
tableOutput("rawdata"),
tableOutput("dayconsumption"))
)
)
)
# RawData import
coffeedata = fread("C:/temp/ProductList.csv")
setDF(coffeedata)
coffeedata$Date = as.Date(coffeedata$Date, "%d.%m.%Y")
# Products a day counter
countcoffee <- function(timeStamps) {
Dates <- as.Date(strftime(coffeedata$Date, "%Y-%m-%d"))
allDates <- seq(from = min(Dates), to = max(Dates), by = "day")
coffee.count <- sapply(allDates, FUN = function(X) sum(Dates == X))
data.frame(day = allDates, coffee.count = coffee.count)}
# Making a DF with day consumption
daylicounter = countcoffee(df$coffee.date)
server <- shinyServer(function(input, output) {
output$structure = renderPrint({
str(coffeedata)
})
# Raw Data
output$rawdata = renderTable({
head(coffeedata)
})
output$dayconsumption = renderTable({
head(daylicounter)
})
# GGPLOT2
output$plot_daycount = renderPlot({
DatesMerge = input$DatesMerge
ggplot(daylicounter[daylicounter == DatesMerge], aes(daylicounter$day, daylicounter$coffee.count)) +
geom_line(color = "orange", size = 1)
scale_x_date(breaks = "3 month",
date_labels = "%d-%m-%Y")
# Try outs
# ggplot(daylicounter[month(day) == month(DatesMerge)], mapping = aes(day = day)) +
# geom_line(color = "orange", size = 1)
# scale_x_date(breaks = "3 month",
# date_labels = "%d-%m-%Y")
})
})
shinyApp(ui, server)
I appreciate your help

Answer 1

As noted by #Kevin, you need to use input$DatesMerge[1] and input$DatesMerge[2] when subsetting your data. For clarity, this can be done in a separate step. Try something like this in your server:
output$plot_daycount = renderPlot({
DatesMerge <- as.Date(input$DatesMerge, format = "%Y-%m-%d")
sub_data <- subset(daylicounter, day >= DatesMerge[1] & day <= DatesMerge[2])
ggplot(sub_data, aes(x = day, y = coffee.count)) +
geom_line(color = "orange", size = 1) +
scale_x_date(breaks = "3 month", date_labels = "%d-%m-%Y")
})
Edit Additional question from OP was asked:
Why does my date format look normal with str(coffeedata) but with
head(coffeedata) the date is just a number?
renderTable uses xtable which may have trouble with dates. You can get your dates to display correctly by converting to character first (one option):
output$rawdata = renderTable({
coffeedata$Date <- as.character(coffeedata$Date)
head(coffeedata)
})
output$dayconsumption = renderTable({
daylicounter$day <- as.character(daylicounter$day)
head(daylicounter)
})
See other questions on this topic:
as.Date returns number when working with Shiny
R shiny different output between renderTable and renderDataTable

Answer 2

Welcome to R and Shiny, you are off to a great start. Few things:
I don't recommend you using = in shiny, majority of the cases you want to use <-
To simplify code, no reason to add a variable like DatesMerge. It adds no value (at least in the code above)
For a dual slider, you need to tell shiny which end to pick. input$DatesMerge doesn't mean anything but input$DatesMerge[1] does.
When asking for help, it is always better to add a subset of data within the code itself. You tend to get more help and it is easier to run for the person trying to help (like me I was too lazy to download the file and place it in a folder so I didn't run it)
You need to account for a range of dates in your slider when subsetting the data; you also for the , when subsetting the data.
ggplot(daylicounter[daylicounter %in% input$DatesMerge[1]:input$DatesMerge[2],], aes(daylicounter$day, daylicounter$coffee.count)) +
geom_line(color = "orange", size = 1) +
scale_x_date(breaks = "3 month",
date_labels = "%d-%m-%Y")