Vary Plots By Different Date Ranges In RShiny - r

Question

I am trying to make a shiny app that plots a custom ggplot plot1 depending on the different dates.
The parameter of plot1 is days which plots by different dates as the days are specified accordingly. However, I just can't figure out how to integrate into the server part of shiny. Here is my best approach:
# create sample data frame with dates
set.seed(1)
date = seq(Sys.Date(), by = "day", length.out = 30)
number = 100 * rnorm(30)
df = data.frame(date = date, number = number)
head(df)
# Plot
library(ggplot2)
library(shiny)
library(dplyr)
plot1 <- function(days) {
df %>% filter(between(date, max(df$date) - days, max(df$date))) %>%
ggplot(aes(x = date, y = number)) +
geom_line() +
theme_classic()
}
# Shiny
ui <- fluidPage(
dateRangeInput(
inputId = "daterange",
label = "Select the date range",
start = min(df$date),
end = max(df$date),
),
plotOutput("plotA")
)
server <- function(input, output, session) {
output$plotA <- renderPlot({
plot1(input$daterange)
})
}
shinyApp(ui, server)

Answer 1

Is filter a masked function for you? You can try using a qualified function call to filter via dplyr::filter().
Other than that, as the other user pointed out, input$daterange is a vector with 2 values - a "beginning" (input$daterange[1]) and an "end" (input$daterange[2]). You mentioned that you tried changing input$daterange[1] or [2], but it doesn't work: I presume that means you changed your call to plot(input$daterange) in server, right? You should be changing and specifying that up in your declaration of that function. Since you define the date from input$daterange based on min(df$date) and max(df$date) already, you can just use days[1] and days[2] to refer to the min and max of the user input. Maybe like this?
plot1 <- function(days) {
df %>% dplyr::filter(between(date, days[1], days[2])) %>%
ggplot(aes(x = date, y = number)) +
geom_line() +
theme_classic()
}
Finally, I have had some issues displaying plots from ggplot in shiny apps myself. In order to show the plot, I store in a variable, and then explicity show the plot with print(). Example:
myPlot <- ggplot(df, aes(x=..., y=...)) + geoms_...
print(myPlot)
If I simply call ggplot without the print() after, it does not always work as intended.