plot dygraph from a list in shiny - r

Question

I wish to plot xts from a list of xts series by selecting the name of each list.
I am not understunding how reactivity and list selection works
library(zoo)
library(dygraphs)
library(xts)
d <- seq(as.Date("2020/01/01"), as.Date("2020/05/01"), "months")
xts1 <- xts(rnorm(5),order.by = d)
xts2 <- xts(rnorm(5),order.by = d)
xts3 <- xts(rnorm(5),order.by = d)
l <- list(xts1,xts2,xts3)
names(l) <- c("uno","dos","tres")
Creation of list of xts objects
library(shiny)
# Define UI for application that draws a histogram
ui <- fluidPage(
# Application title
titlePanel("Old Faithful Geyser Data"),
# Sidebar with a slider input for number of bins
sidebarLayout(
sidebarPanel(
selectInput(names,names,names(l))
),
# Show a plot of the generated distribution
mainPanel(
dygraphOutput("plot")
)
)
)
# Define server logic required to draw a histogram
server <- function(input, output) {
#option 1
p <- reactive({
input$names
})
output$plot <- renderDygraph({
l[[p]]
})
# option 2
output$plot <- renderDygraph({
l[[input$names]]
})
}
# Run the application
shinyApp(ui = ui, server = server)
It doesn´t work neither ways.
Appreciate :)

Answer 1

Four things are wrong in your code:
in selectInput(), you must use quotation marks for the two first arguments, that correspond to inputId and name.
you can't use output$plot twice in server. plot must be a unique id, so you could have output$plot1 and output$plot2 for instance. This means that you also need to have two dygraphOutput (or plotOutput, or ...) in the ui part.
when you define a reactive(), you must use parenthesis when you call it afterwards, e.g p() and not p
in renderDygraph (or renderPlot, or...), you still need to put the code to create the plot, as if it was in regular R and not R Shiny.
Therefore, your corrected code is:
library(zoo)
library(dygraphs)
library(xts)
library(shiny)
d <- seq(as.Date("2020/01/01"), as.Date("2020/05/01"), "months")
xts1 <- xts(rnorm(5),order.by = d)
xts2 <- xts(rnorm(5),order.by = d)
xts3 <- xts(rnorm(5),order.by = d)
l <- list(xts1,xts2,xts3)
names(l) <- c("uno","dos","tres")
# Define UI for application that draws a histogram
ui <- fluidPage(
# Application title
titlePanel("Old Faithful Geyser Data"),
# Sidebar with a slider input for number of bins
sidebarLayout(
sidebarPanel(
selectInput("names", "names", names(l))
),
# Show a plot of the generated distribution
mainPanel(
dygraphOutput("plot1"),
dygraphOutput("plot2")
)
)
)
# Define server logic required to draw a histogram
server <- function(input, output) {
p <- reactive({
input$names
})
output$plot1 <- renderDygraph({
dygraph(l[[p()]])
})
output$plot2 <- renderDygraph({
dygraph(l[[input$names]])
})
}
# Run the application
shinyApp(ui = ui, server = server)