Python / R Check density peaks in ggplot2

Question

I have two sets of data formed as follows:

A= {id1: 0.3, id2: 0.1, id3: 0.3 ... idn: 0.2}

B= {id1: 0.01, id2: 0.04, id3: 0.75 ... idn: 0.9}

I used the function ggplot R to plot the densities values on the same graph, thus:

I would like to know what are the id’s that are in the peaks of each density. For example, what are the id’s that are at the peak (in red) of each density?

I would like to know if the id’s are different or equal in the peaks, ie in the high density values.

Answer 1

You can take the data from the graph generated by ggplot2 by asking the print explicitly.

For example, let’s generate a histogram:

rm(list = ls())
library(ggplot2)
set.seed(10)
df <- data.frame(x = rnorm(10000))
grafico <- ggplot(df, aes(x = x)) + geom_density()
grafico

To take the data from the graph and so know what is the maximum value, ask the print explicitly, save the data and see the maximum value of the density:

dados_grafico <- print(grafico)$data[[1]]
dados_grafico[which.max(dados_grafico$density), c("x","density")]
             x   density
238 -0.1253751 0.3963933

In this case the maximum occurs in x = -0.1253751 with a density of 0.3963933.