R and ggplot2 : plot with factors on both axis

Question

My data frame looks like this :

data
>
          | Segment 1 | Segment 2  | Segment 3
Segment 1 | 0.6861964 | 0.16669839 | 0.14710523
Segment 2 | 0.2211293 | 0.69263231 | 0.08623838
Segment 3 | 0.2595055 | 0.05354549 | 0.68694899

I would like to use in both axis Segment 1, Segment 2 and Segment 3 and use the values inside the table as parameters to have points of different sizes.

What I tried for the moment is to add a column Segments to the above data frame and did a melt() in order to obtain the following table:

data_melt <- melt(data, id = "Segments")
>
  | Segments  | variable  | value
1 | Segment 1 | Segment 1 | 0.68619638
2 | Segment 2 | Segment 1 | 0.22112931
3 | Segment 3 | Segment 1 | 0.25950552
4 | Segment 1 | Segment 2 | 0.16669839
5 | Segment 2 | Segment 2 | 0.69263231
6 | Segment 3 | Segment 2 | 0.05354549

Then trying to plot it I am stuck and could not find a ressource solving my problem.

ggplot(test, aes(x = Segments, y = variable, size = value))
    geom_point()

It plots the axis but no point appears and I get the following message:

geom_point: na.rm = FALSE
stat_identity: na.rm = FALSE
position_identity

I would like the output to look like this:

In aes, x and y are set to a string variables (x="Segment 1"), not a numeric value. You are attempting to plot strings as points. — steveb
– steveb, Commented Feb 17, 2016 at 17:19
How should I do it ? Generaly when I use string variable in only one axis, it doesn't complain. I though that in data_melt the fact that they were on the same line was enough — Yohan Obadia
– Yohan Obadia, Commented Feb 17, 2016 at 17:34
So on the x-axis you want to plot a factor essentially. For the y-axis, what are you trying to capture ? If you are trying to capture the variable number, you will have to just have the values 1 or 2 in the variable column. — steveb
– steveb, Commented Feb 17, 2016 at 17:40
I updated my question to be clearer. What I would like is that the column value would define the size of each circle. — Yohan Obadia
– Yohan Obadia, Commented Feb 17, 2016 at 17:52

Manfred Mustermann · Accepted Answer · 2016-02-17 17:59:57Z

2

I was able to reproduce by

data_melt <-  data.frame(seg=c(1,2,3,1,2,3),var=c(1,1,1,2,2,2),value=runif(6))

> ggplot(test, aes(x = Seg, y = var, size = value))
Error: No layers in plot
> geom_point()
geom_point: na.rm = FALSE 
stat_identity:  
position_identity: (width = NULL, height = NULL)

basically you forgot a +

 ggplot(data_melt, aes(x = seg, y = var,size=value))+geom_point()

answered Feb 17, 2016 at 17:59

Manfred Mustermann

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1 Comment

Yohan Obadia Over a year ago

Ok... I think I am a bit ashamed of this one... Thank you !

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