R - Shiny App - Using plotly to visualize shinyMatrix input - r

Question

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I would like to visualize the input of a shinyMatrix using a plotlymesh3d-plot. I was using a for-loop to convert the matrix input into a data frame having 3 columns (x, y and z) - see below. This works when being run outside the shiny app. Unfortunately, I'm stuck with using this for-loop inside a reactive() environment to pass this into plot_ly(). It says "object of type closure is not subsettable". I read, that this error often comes if you don't treat your reactive object as a function (which I did).
I know that I'm a beginner and I don't have much clue about the syntax of a shiny app. Most likely I did a supid mistake :-) But I don't know how to solve this.
Thanks!
library(shiny)
library(shinyMatrix)
ui <- fluidPage( titlePanel("shinyMatrix: Simple App"),
sidebarPanel(width = 6,tags$h4("Data"),
matrixInput("mat",
value = matrix(1:100, 10, 10),
rows = list(names=T, extend = TRUE),
cols = list(names = TRUE))),
mainPanel(width = 6,
plotlyOutput(
"plotly",
width = "100%",
height = "400px",
inline = FALSE,
reportTheme = TRUE
)))
server <- function(input, output, session) {
df <- data.frame(x="", y="", z="")
df <- reactive({
n=1
for(i in 1:nrow(input$mat)){
for(j in 1:ncol(input$mat)){
df[n,1] <- j*laenge
df[n,2] <- i*laenge
df[n,3] <- input$mat[i,j]
n=n+1
}
}
})
output$plotly <- renderPlotly({plot_ly(df(), x=~x, y=~y, z=~z, type="mesh3d")})
}
shinyApp(ui, server)

Answer 1

Main issue is that you used the same name df for both the reactive and the dataframe. Additionally your reactive has to return something to make your code work, i.e. return the dataframe after your for-loops.
server <- function(input, output, session) {
dd <- data.frame(x = NA, y = NA, z = NA)
df <- reactive({
n <- 1
for (i in 1:nrow(input$mat)) {
for (j in 1:ncol(input$mat)) {
dd[n, 1] <- j * laenge
dd[n, 2] <- i * laenge
dd[n, 3] <- input$mat[i, j]
n <- n + 1
}
}
dd
})
output$plotly <- renderPlotly({
plot_ly(df(), x = ~x, y = ~y, z = ~z, type = "mesh3d")
})
}