Pairing colors to factors in ggplot2

Question

I have a variable Channel which is factor with levels A,B,C. If you run my shiny up level A is red points level B green points and level C blue points. When I uncheck A level to make it disspear colous for B and C change and that is what I want to prevents. So every level should have it's colour. I tried to play around a bit with scale manual etc but no success.

########### UI.R
library(shiny)

shinyUI(fluidPage(
    titlePanel("Hello Shiny!"),
    sidebarLayout(
        sidebarPanel(
            checkboxGroupInput(inputId="check1_1", label="Select channel", choices=c("a","b","c"),
                               selected=c("a","b","c"))
        ),

        mainPanel(
            plotOutput("myplot")
        )
    )
))

########## Server.R
shinyServer(function(input, output) {

df<-data.frame(Channel=sample(letters[1:3],100,replace = TRUE),
                        x=runif(100),
                        y=runif(100))

df1<-reactive({

    y<-as.factor(input$check1_1)
    df1<-df[which(df$Channel %in% y), ]
}) 
output$myplot<-renderPlot({
    ggplot(df1(),aes(x = x,y = y,colour=Channel))+geom_point(size=6)
})  


})

A couple ways to do it, shown [here](http://stackoverflow.com/questions/21322819/generating-a-consistent-dynamic-color-palette-in-ggplot-within-a-loop) and [here](http://stackoverflow.com/questions/19068432/ggplot2-how-to-use-same-colors-in-different-plots-for-same-factor#) — aosmith, Jul 01 '16 at 17:59
I haven't tested it with your code, but I think you can just add `+ scale_color_discrete(drop=FALSE)` to your ggplot code. This will work regardless of which rows are removed from the data, so long as the underlying levels of the factor don't change. — eipi10, Jul 01 '16 at 18:06

score 2 · Accepted Answer · answered Jul 01 '16 at 18:37

2

You can just add + scale_color_discrete(drop=FALSE) to your ggplot code. This will work regardless of which rows are removed from the data, so long as the underlying levels of the factor don't change.

answered Jul 01 '16 at 18:37

eipi10

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Pairing colors to factors in ggplot2

1 Answers1