CODEWITHSUNDEEP
rggplot2
user3233488
user3233488

Reputation: 7

How to add two distributions to a density in ggplot2

I want to add two sets of bowling scores onto the same distribution in ggplot2, I don't have the same amount of observations in each group but I would like to plot them on top of eachother. Below is the code I have.

    m <- ggplot(bowling, aes(x = as.numeric(Kenny)))
    n <- ggplot(bowling, aes(x= as.numeric(Group)))
    m + n geom_density()

and this is the error.

    Error in p + o : non-numeric argument to binary operator
    In addition: Warning message:
    Incompatible methods ("+.gg", "Ops.data.frame") for "+"

I just want to plot them on top of eachother but I can't figure out what the problem is.

Upvotes: 0

Views: 1646

Answers (1)

msoftrain
msoftrain

Reputation: 1037

The problem is that you're adding a single geom_density layer to two different plots (m and n) that have different aesthetic mappings.

Here is a potential solution, if I understood your question correctly.

First, creating a small sample dataset

kenny <- rnorm(100, 20, 2)  
group <- rnorm(100, 15, 2)  
bowling <- data.frame(kenny, group)

Second, plotting first a geom_density layer for kenny as an aesthetic, and then adding a geom_density layer for a different aesthetic, namely group. 

ggplot(bowling, aes(x = kenny)) +  
geom_density() + geom_density(aes(x=group), colour="red")

Here is what you obtain:

enter image description here

Upvotes: 1

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