# Density plot, scale it to 0-1

Doubt regarding density plot what is the scale being plotted in the Y axis.Is it possible to scale it to 1?.

This is my code

w <- read.csv("Normal_Myeloid_Dev_stages/Myeloid_non_coding_non_CDS_CORRVALUE.txt",header = TRUE)
#names(w)[1] = "Sample"

#w.plot <- melt(w)

df <- w

df_melt=melt(df,id.vars="Sample")
tail(df_melt)
df_melt$$Group <- gsub('[0-9]', '',df_melt$$variable)

p1 <- ggplot(aes(x=value, colour=Group), data=df_melt)
p1 + geom_density()

ggplot(df_melt, aes(x = value,y=..density.., fill = Group)) + geom_density(alpha = 0.5)+
theme_bw(base_size=30)+
theme(axis.text.x=element_text(angle = 45, size=45, face="bold", hjust = 1),
axis.text.y=element_text(angle=0, size=50, face="bold", vjust=0.5),
plot.title = element_text(size=40, face="bold"),
legend.title=element_blank(),
legend.key.size=unit(1, "cm"),      #Sets overall area/size of the legend
legend.text=element_text(size=30))

dev.off()


Second question regarding finding the overlapping area between various condition let say I have four condition and i want to find out what is the overlapping or intersecting area between them .

I tried on of the stack solution firstly is it the right way to do it for finding overlap? if yes can i try finding all the condition overlap such as I have HSC,CMP,GMP and Mono.

FDensity = approxfun(density(df_melt$$value[df_melt$$Group=="CMP"], from=.80, to=1))
MDensity = approxfun(density(df_melt$$value[df_melt$$Group=="Mono"], from=.80, to=1))
plot(FDensity, xlim=c(.80,1), ylab="Density")

FminusM = function(x) { FDensity(x) - MDensity(x) }
Intersect = uniroot(FminusM, c(.8, 1))$root points(Intersect, FDensity(Intersect), pch=20, col="red") integrate(MDensity, .80,Intersect)$$value + integrate(FDensity, Intersect, 1)$$value  Any suggestion or help would be really appreciated My dataframe small subset dput(head(df)) structure(list(Sample = structure(c(9L, 10L, 11L, 12L, 1L, 2L ), .Label = c("CMP1", "CMP2", "CMP3", "CMP4", "GMP1", "GMP2", "GMP3", "GMP4", "HSC1", "HSC2", "HSC3", "HSC4", "Mono1", "Mono2", "Mono3", "Mono4"), class = "factor"), HSC1 = c(1, 0.901758000194052, 0.880971458703505, 0.900098712568466, 0.873507054094022, 0.906315987662777 ), HSC2 = c(0.901758000194052, 1, 0.945122894369186, 0.955453795442752, 0.844777154811663, 0.960260413763721), HSC3 = c(0.880971458703505, 0.945122894369186, 1, 0.931891528389177, 0.829521543809914, 0.93636611655036 ), HSC4 = c(0.900098712568466, 0.955453795442752, 0.931891528389177, 1, 0.852155096935692, 0.947192034704188), CMP1 = c(0.873507054094022, 0.844777154811663, 0.829521543809914, 0.852155096935692, 1, 0.88406635204624 ), CMP2 = c(0.906315987662777, 0.960260413763721, 0.93636611655036, 0.947192034704188, 0.88406635204624, 1), CMP3 = c(0.883085447599108, 0.928929790213059, 0.937278860333014, 0.923139729112196, 0.870595169861622, 0.958330253497026), CMP4 = c(0.903500691840647, 0.931015449611016, 0.915510499719426, 0.949501343959892, 0.89151869084162, 0.960206335031192 ), GMP1 = c(0.859320159223793, 0.833454007185579, 0.821479398953591, 0.837605565046685, 0.856892209387879, 0.8612685942226), GMP2 = c(0.894680165774456, 0.944129985346879, 0.92461599550388, 0.937108867595306, 0.875930650641323, 0.966512850930959), GMP3 = c(0.881416749993221, 0.925001567707159, 0.923015420025178, 0.920758302664238, 0.863998116268766, 0.95069438729762 ), GMP4 = c(0.887230702792805, 0.911614382740949, 0.898704725226052, 0.938310378760322, 0.875956580458754, 0.93865124308053), Mono1 = c(0.80834274546097, 0.803706049167148, 0.785535924609134, 0.794438848049474, 0.794402126200663, 0.810382054101301), Mono2 = c(0.829928035079747, 0.868021129791583, 0.848929312833536, 0.852953184941131, 0.818074585324121, 0.880490870699251 ), Mono3 = c(0.834028389107401, 0.859818911060746, 0.852694253707916, 0.85039434449057, 0.82251614206182, 0.872740655210769), Mono4 = c(0.832524159512094, 0.858444209302146, 0.84397886802844, 0.862850406374668, 0.818436260136434, 0.870293804485003)), row.names = c(NA, 6L), class = "data.frame")  ## 1 Answer I'm not fully to have understood your second questions, but first, if you want to scale the density to 1, you can use y= ..scaled.. in your aes: library(tidyverse) df %>% pivot_longer(., everything(), names_to = "Variable", values_to = "Value") %>% ggplot(., aes(x = Value, y = ..scaled.., fill = Variable)) + geom_density(alpha = 0.4)  Now regarding the second question, if you are looking for the overlap between each of your density, you can use the package overlapping as specified in the post you are referring: https://stackoverflow.com/questions/41914257/calculate-area-of-overlapping-density-plot-by-ggplot-using-r?noredirect=1&lq=1 library(overlapping) library(lattice) x <- list(D1 = D1, D2 = D2, D3 = D3, D4 = D4) overlap(x, plot = TRUE)  And if you want to extract the value of overlap, you can get it: OV <- overlap(x)$OV

> OV
D1-D2     D1-D3     D1-D4     D2-D3     D2-D4     D3-D4
0.5971760 0.3171644 0.7566528 0.4926057 0.6683083 0.3756224


Is it what you are looking for ? Or did I misunderstood your question ?

Dummy Dataset

# Dummy example:
D1 = rnorm(100, mean =1, sd = 2)
D2 = rnorm(100, mean = 2, sd = 2)
D3 = rnorm(100, mean = 3, sd = 1)
D4 = rnorm(100,mean = 1.5, sd = 1.5)

df = data.frame(D1,D2,D3,D4)


EDIT: Using reproducible example provided in the question For plotting geom_density of your data:

library(tidyverse)
df %>% pivot_longer(., -Sample, names_to = "Variable", values_to = "Value") %>%
mutate(New_Var = gsub("\\d","",Variable)) %>%
ggplot(., aes(x = Value, y = ..scaled.., fill = New_Var))+
geom_density(alpha = 0.4)


And to find the overlap:

d<- df %>% pivot_longer(., -Sample, names_to = "Variable", values_to = "Value") %>% mutate(New_Var = gsub("\\d","",Variable))
a <- split(d$$Value, unique(d$$New_Var))

g <- overlap(a, plot = TRUE)\$OV


I don't think there is an option in the overlap function to scaled each overlap plot to 1 but these plot are using ggplot and so, I imagine you can extract their points and scaled them by plotting them separately in ggplot2.

• excellent you have got my question precisely let me give it a try on my data set
– kcm
Dec 17, 2019 at 5:14
• a little doubt for the second part since I have multiple biological replicate ,since you made a list x <- list(D1 = D1, D2 = D2, D3 = D3, D4 = D4) as you have each individual column which you are overlapping .I will attach a small part of my dataframe to show my doubt.
– kcm
Dec 17, 2019 at 5:26
• I edited my answer to show the use of your example dataset. However, I'm not sure it is possible to scaled each overlap plot to 1 (probably as you can extract individual data for each plot). Also, as you don't have massive difference in the amplitude of each density, I'm not sure the scaled function is really required for that.
– dc37
Dec 17, 2019 at 22:23
• Could potentially be two subpopulations of the GMP group...
– dc37
Jan 25, 2020 at 5:59
• Yes, either one or two of your biological replicate is different from others, or you have two subpopulations in all of your replicate. I think, you can try to plot their densities separately to see how values of each replicate is distributed. Either, they are all single peak but with different means (which after merging create two peaks), or each replicate have two peaks.
– dc37
Jan 25, 2020 at 6:18