Density plot in ggplot2 with y value taken into account

Question

My data contains x axis points and y value for each x axis point. The x axis points are not evenly distributed. I need to visualize how the x axis points are clustered and how does the y value appears for such clusters. To see how the x values are clustered I can plot density plot on x value, however it does not reflect the y values at that cluster. for example- if 100 points (lets say) on x axis are very close to each other and all has positive y value I want my plot go up at that point, if those 100 points has negative y value I want my plot go down the zero line in plot, if those 100 points has both positive and negative y values I want my plot be around zero point. Similarly, even if the those 100 points all has positive value, if they are scattered along long distance I want the plot be near the zero line.

In short, density of x points and its y value both matters to me and I want to plot smooth line. Could anyone help me with this?(stat_smooth did not do the work as it makes my plot almost straight line)

here are my x and y axis values (I did not know how to insert table here)

x axis values

Y axix values:

y_value
16.7
14.3
10.5
18.2
20.0
16.7
14.3
10.4
27.3
22.2
11.1
-18.2
-10.1
-13.3
-26.4
-13.3
-15.4
14.3
15.4
11.7
26.7
18.2
64.7
21.2
20.0
11.8
-17.9
25.0
14.2
20.0
18.2
12.5
12.5
10.5
11.1
12.5
14.3
-20.0
12.5
-20.0
16.7
13.3
18.2
20.0
30.0
20.0
11.8
-18.8
20.0
20.0
12.5
18.8
13.3
-15.4
18.2
18.9
28.6
20.0
12.5
16.1
15.4
10.5
13.3
29.7
23.1
18.2
14.3
12.5
12.5
16.7
11.1
20.0
18.2
18.2
13.2
13.3
11.8
15.4
14.3
23.8
18.2
33.3
18.2
-12.5
12.5
23.1
21.7
14.3
16.7
11.1
16.7
12.5
11.1
12.5
18.2
12.5
11.0
20.0
18.2
15.8
10.5
10.2
10.5
14.3
11.8
25.0
13.8
16.4
16.7
-18.2
18.2
16.7
18.2
18.2
11.8
12.5
14.3
17.9
10.5

jlhoward · Accepted Answer

Note: In what follows, I've combined your x and y data into a data frame df with columns x and y.

Looking at a simple scatter plot, it appears that your data is grouped more or less into five clusters:

with(df,plot(x,y))

To see the distribution in both the x and y-direction you need a 2-dimensional kernal density estimate, which is available in package MASS. You can then plot this in 3 dimensions (with the density as z) using the rgl package.

library(MASS)     # for kde2d(...)
library(rgl)      # for open3d(...) and surface3d(...)
dens <- kde2d(df$x,df$y)
zlim    <- range(dens$z)
palette <- rev(heat.colors(10))
col     <- palette[9*(dens$z-zlim[1])/diff(zlim) + 1] # assign colors to heights for each point
with(dens,open3d(scale=c(x=1/diff(range(x)),y=1/diff(range(y)),z=1/diff(range(z)))))
with(dens,surface3d(x,y,z, color=col))
title3d(xlab="X",ylab="Y")

Density plot in ggplot2 with y value taken into account

Answers (1)

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