Subsetting data in shiny server.R file - r

Question

I am trying to get a simple Shiny app to work (this would be the start of something bigger). My problem is that subsetting data in the sever.R part of the app does not seem to work at all for me.
The error message is:
Error in eval(expr, envir, enclos) : object 'localA3' not found
Here's my server.R file:
# server.R
library(ggmap)
library(scales)
library(grid)
localA <- read.csv("local7.csv", header=TRUE)
shinyServer(
function(input, output) {
output$map <- renderPlot({
sub <- switch(input$sub,
"a" = "a",
"b" = "b",
"c" = "c")
opt <- switch(input$opt,
"data" = "data",
"obs" = "obs")
localx = reactive({
x <- subset(localA, factor==paste(sub))
return(x)
})
localA3 <- localx()
testmapA <- qmap("England", zoom = 6, color = "bw", legend = "topleft")
testmapA +
geom_point(aes(x = lon, y = lat, colour = localA3$opt, size = localA3$opt), data = localA3)
})
}
)
...and this is my UI.R file:
# UI.R
shinyUI(fluidPage(
titlePanel("A Shiny Example"),
sidebarLayout(
sidebarPanel(
helpText("Create maps with random data for UK local authorities."),
selectInput("sub",
label = "Choose a category to display",
choices = c("a", "b", "c"),
selected = "a"),
selectInput("opt",
label = "Choose a variable to display",
choices = c("data", "obs"),
selected = "data"),
sliderInput("range",
label = "Range of interest:",
min = 0, max = 100, value = c(0, 100))
),
mainPanel(plotOutput("map"))
)
))
For whatever reason R tells me that it can't find the object 'localA3'. I have tried to program the subsetting part of the code in many different ways now - from reactive expressions over functions to simple R-code. What works outside of Shiny doesn't work in the server.R program.
Can anyone give me any hints on what I might be doing wrong?
The first ten entries of my base dataset 'local7.csv' are as follows:
lon lat data obs factor
1 -0.1277583 51.5073509 87.828234 20.49259318 a
2 0.1293497 51.5464828 68.79663358 98.0480588 a
3 -0.1997 51.6444 24.35460542 76.77994522 b
4 0.154327 51.439933 71.51349632 28.05491455 a
5 -0.2710568 51.5672808 91.31933313 69.15576621 c
6 0.013156 51.406025 57.98920169 56.12171479 a
7 -0.1588255 51.5517059 45.68928313 29.73514486 a
8 -0.098234 51.376165 29.47027315 96.1460748 b
9 -0.3415002 51.5250257 36.46005588 76.66948508 c
10 -0.0837 51.6516 43.57721438 50.65123884 c

Answer 1

You need to change your aes call to aes_string and make all elements strings so you are consistent with geom_point. Before you are using both objects and strings. The following small change at the end of you uiR works for me.
testmapA +
geom_point(aes_string(x = "lon", y = "lat", colour = input$opt, size = input$opt), data = localA3)