Shiny + ggplot: How to subset reactive data object? - r

Question

I am making a shiny app, that shows the user a ggplot after he selects the daterange he is interested in (= the range for the x-axis). So I guess I need to define a reactive data object (correct?).
The ggplot has some subsetting in it. R tells me that reactive data object is not subsettable. In my rookie understanding of ggplot, the subsetting has to be done inside the geom_bar(), geom_line() statements in order to obtain the graph that I want.
Can anyone suggest me how to proceed with the subsetting?
And how to reference the factor category in generating colors for the graph?
Thanks!
sample data
A = c(3, 4, 3, 5)
B = c(2, 2, 1, 4)
Z = c(1, 2, 1, 2)
R = c(-2, -1, -3, 0)
S = c(7,7,7,9)
mydata = data.frame(cbind(A,B,Z,R,S))
dates = c("2014-01-01","2014-02-01","2014-03-01","2014-04-01")
mydata$date = as.Date(dates)
mydata.m = melt(mydata,id="date")
names(mydata.m) = c("variable", "category","value")
shiny server: select observations as per user input (dateRangeInput)
data.r = reactive({
a = subset(mydata.m, variable %in% input$daterange)
return(a)
})
shiny server: make the plot
output$myplot = renderPlot({
# ggplot with proper reference to reactive function <<data.r()>>
s = ggplot(data.r(), aes(x=variable, fill=category)) +
# bars for categories A, B, Z: needs subsetting the data... but how?
+ geom_bar(data=subset(data.r(), category %in% c("A","B")), aes(y=value), stat="identity", position="stack")
+ geom_bar(subset=.(category=="Z"), aes(y=-value), stat="identity")
# lines for categories R, S: same.
+ geom_line(subset=.(category=="R"), aes(y=value))
+ geom_line(subset=.(category=="S"), aes(y=value))
# how to reference the factor <<category>> in reactive function <<data.r()>>?
+ scale_fill_manual(breaks = levels(category), values = mycolorgenerator(length(levels(category))))
print(s)
})
UI.R
# INPUT PART
library(shiny)
shinyUI(pageWithSidebar(
# Application title
headerPanel("My App"),
sidebarPanel(
dateRangeInput("daterange", "Date range:",
start = "2014-01-01",
end = "2014-04-01",
min = "2014-01-01",
max = "2014-04-01",
format = "dd/mm/yyyy",
separator = "-"),
submitButton(text="Update!")
),
# -----------------------------------------------
# OUTPUT PART
mainPanel(
tabsetPanel(
tabPanel("Tab 1", h4("Head 1"),plotOutput("myplot"))
)
)
))
SERVER.R
library(reshape)
library(shiny)
library(ggplot2)
# GEN DATA -----------------------------------------------
A = c(3, 4, 3, 5)
B = c(2, 2, 1, 4)
Z = c(1, 2, 1, 2)
R = c(-2, -1, -3, 0)
S = c(7,7,7,9)
mydata = data.frame(cbind(A,B,Z,R,S))
dates = c("2014-01-01","2014-02-01","2014-03-01","2014-04-01")
mydata$date = as.Date(dates)
mydata.m = melt(mydata,id="date")
names(mydata.m) = c("variable", "category","value")
# SERVER -----------------------------------------------
shinyServer(function (input, output) {
# DATA
data.r = reactive({
a = subset(mydata.m, variable %in% input$daterange)
return(a)
})
# GGPLOT
mycolorgenerator = colorRampPalette(c('sienna','light grey'))
output$myplot = renderPlot({
# ggplot with proper reference to reactive function <<data.r()>>
s = ggplot(data.r(), aes(x=variable, fill=category)) +
# bars for categories A, B, Z: needs subsetting the data... but how?
geom_bar(data=subset(data.r(), category %in% c("A","B")), aes(y=value), stat="identity", position="stack") +
geom_bar(subset=.(category=="Z"), aes(y=-value), stat="identity") +
# lines for categories R, S: same.
geom_line(subset=.(category=="R"), aes(y=value)) +
geom_line(subset=.(category=="S"), aes(y=value)) +
# how to reference the factor <<category>> in reactive function <<data.r()>>?
scale_fill_manual(breaks = levels(category), values = mycolorgenerator(length(levels(category))))
print(s)
})
})

Answer 1

(The complete server.R and ui.R really helped)
I'm not sure where you got the .() function from or the idea that geom_bar has a subset= parameter. But here's an updated renderPlot that doesn't seem to generate any errors at least
output$myplot = renderPlot({
dd<-data.r()
# ggplot with proper reference to reactive function <<data.r()>>
s = ggplot(dd, aes(x=variable, fill=category)) +
# bars for categories A, B, Z: needs subsetting the data... but how?
geom_bar(data=subset(dd, category %in% c("A","B")), aes(y=value),
stat="identity", position="stack") +
geom_bar(data=subset(dd, category=="Z"), aes(y=-value), stat="identity") +
# lines for categories R, S: same.
geom_line(data=subset(dd, category=="R"), aes(y=value)) +
geom_line(data=subset(dd, category=="S"), aes(y=value)) +
scale_fill_manual(breaks = levels(dd$category),
values = mycolorgenerator(length(levels(dd$category))))
print(s)
})
Mostly I changed the data= to explicit subset() calls