Why is this simple R Shiny output not plotting with ggplot? - r

Question

In running the below code, I'm not sure why it's not plotting. In other, more involved versions of this code it does plot; I've done line-by-line comparisons and can't see why it doesn't plot in this case. I've played with req(), if(isTruthy()...)) statements, with no luck. I tested the interpol() custom function in the console, and it works fine as shown in the image at the bottom of this post.
library(ggplot2)
library(shiny)
library(shinyMatrix)
interpol <- function(a, b) { # a = periods, b = matrix inputs
c <- rep(NA, a)
c[1] <- b[1]
c[a] <- b[2]
c <- approx(seq_along(c)[!is.na(c)], c[!is.na(c)], seq_along(c))$y # << interpolates
return(c)
}
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput('periods', 'Modeled periods (X variable):', min=1, max=10, value=10),
matrixInput("matrix1",
label = "Matrix 1:",
value = matrix(c(5), ncol = 1, dimnames = list("Base rate",NULL)),
cols = list(names = FALSE),
class = "numeric"),
matrixInput("matrix2",
label = "Matrix 2 (will link to Matrix 1):",
value = matrix(c(10,5), ncol = 2, dimnames = list(NULL,c("X","Y"))),
rows = list(extend = TRUE, delete = TRUE),
class = "numeric"),
),
mainPanel(
plotOutput("plot")
)
)
)
server <- function(input, output, session){
plotData <- reactive({
req(input$periods,input$matrix2) # << this doesn't help
tryCatch(
tibble(
X = seq_len(input$periods),
Y = interpol(input$periods,input$matrix2, drop = FALSE)
),
error = function(e) NULL
)
})
output$plot <- renderPlot({
req(plotData())
plotData() %>% ggplot() +
geom_line(aes(x = X, y = Y, colour = as.factor(Scenario))) +
theme(legend.title=element_blank())
})
}
shinyApp(ui, server)

Answer 1

library(dplyr) was missing function tibble was unknown
Your function interpol doesn't have a drop argument
Object 'Scenario' not found
library(ggplot2)
library(shiny)
library(shinyMatrix)
library(dplyr)
interpol <- function(a, b) { # a = periods, b = matrix inputs
c <- rep(NA, a)
c[1] <- b[1]
c[a] <- b[2]
c <- approx(seq_along(c)[!is.na(c)], c[!is.na(c)], seq_along(c))$y # << interpolates
return(c)
}
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput('periods', 'Modeled periods (X variable):', min=1, max=10, value=10),
matrixInput("matrix1",
label = "Matrix 1:",
value = matrix(c(5), ncol = 1, dimnames = list("Base rate",NULL)),
cols = list(names = FALSE),
class = "numeric"),
matrixInput("matrix2",
label = "Matrix 2 (will link to Matrix 1):",
value = matrix(c(10,5), ncol = 2, dimnames = list(NULL,c("X","Y"))),
rows = list(extend = TRUE, delete = TRUE),
class = "numeric"),
),
mainPanel(
plotOutput("plot")
)
)
)
server <- function(input, output, session){
plotData <- reactive({
# browser()
req(input$periods, input$matrix2) # << this doesn't help
tryCatch(
# drop = FALSE
tibble(
X = seq_len(input$periods),
Y = interpol(input$periods,input$matrix2)
),
error = function(e) NULL
)
})
output$plot <- renderPlot({
req(plotData())
# Error in is.factor: object 'Scenario' not found
# , colour = as.factor(Scenario)
plotData() %>% ggplot() +
geom_line(aes(x = X, y = Y)) +
theme(legend.title=element_blank())
})
}
shinyApp(ui, server)