R shiny: How to loop output plotly graphs - r

Question

I want to draw 20 graphs in shiny by loop and I don't want to write the output one by one. So I am thing doing a loop to output these graphs. I found a very good example in the shiny gallery which shows how to output texts. I tiried it and it worked.
Now my problem is: How can I replace the text output to plotly? I have the plotly ready(to simplify I am not showing here). What I tried is first replace the strong(paste0(.. line with my plotly object. Second, replace renderUI to renderplotly and replace uiOutput to plotOutput. I am getting errors ggplotly has no applicable method for shiny.tag which I understand that plotOutput is not compatible with tagged output. So what can I do here?
server.r:
shinyServer(function(input, output,session) {
lapply(1:2, function(i) {
output[[paste0('b', i)]] <- renderUI({
strong(paste0('Hi, this is output B#', i)) })# to be replaced with a plotly object p
})})
ui.r:
fluidRow(
lapply(1:2, function(i) {
uiOutput(paste0('b', i))
})
)

Answer 1

Check out this example Shiny app that displays a dynamic number of plots: https://gist.github.com/wch/5436415/
I adapted the above app to plot the cars dataset with ggplotly.
library(shiny)
library(ggplot2)
library(plotly)
shinyApp(
##### ui #######
ui = fluidPage(
fluidRow(
sliderInput("n",
"Number of plots",
value = 1, min = 1, max = 5)),
fluidRow(
uiOutput("plots"))
),
##### server ######
server = function(input, output) {
data("cars")
# define max number of plots
max_plots <- 5
# generate the plots
output$plots <- renderUI({
plot_output_list <- lapply(1:input$n, function(i) {
plotname <- paste0("plot", i)
plotlyOutput(plotname)
})
# convert the list to a tagList - this is necessary for the list of
# items to display properly
do.call(tagList, plot_output_list)
})
# call renderPlotly for each plot. Plots are only generated when they are
# visible on the web page
for(i in 1:max_plots) {
# Need local so that each item gets its own number. Without it, the value
# of i in the renderPlotly() will be the same across all instances, because
# of when the expression is evaluated
local({
my_i <- i
plotname <- paste0("plot", my_i)
output[[plotname]] <- renderPlotly({
g <- ggplot(cars, aes(x = speed, y = dist)) +
geom_point() +
labs(title = paste0("Plot ", my_i))
g <- ggplotly(g)
dev.off()
g
})
})
}
}
)
Creating one plot with many subplots:
library(shiny)
library(ggplot2)
library(plotly)
library(grid)
shinyApp(
##### ui #######
ui = fluidPage(
fluidRow(
sliderInput("n",
"Number of plots",
value = 1, min = 1, max = 5)),
fluidRow(
plotlyOutput("plots")
)
),
##### server ######
server = function(input, output) {
data("cars")
# define max number of plots
max_plots <- 5
# generate the plots
output$plots <- renderPlotly({
plot_list <- lapply(1:input$n, function(i) {
g <- ggplot(cars, aes(x = speed, y = dist)) +
geom_point() +
theme(plot.margin = unit(c(3, 1, 1, 1), "lines"))
ggplotly(g)
})
p <- subplot(plot_list[1:input$n], shareX = TRUE, shareY = TRUE) %>%
layout(title = "Car Plots")
dev.off()
p
})
}
)