Plotting multiple variables from a csv file in the same graph. R

Question

I have a csv file ("data.csv") with several columns. My dependent variable is J and my independent variables are S1, S2, S3 and S4.

J  S1  S2  S3  S4  Z
1   4   5   3   2  0
2  12  11  34  44  0
3  12  15  22  21  1
4  10   9  10  11  1

I have managed to plot J and S1:

Reg.data <- read.csv ("C: \\ Users \\ data.csv", header = TRUE, sep = ';')
Library (ggplot2)
Qplot (data = reg.data, x = J, y = mean(S1), color = "red")

Now, I would like to plot (in the same graph) all my independent variables S1, S2, S3, S4 in different colours. I've tried (and I've searched in the forum) but I can not do it.

I would also like to know how to plot three axes: variable J, variables S (on the same axis) and covariable Z.

User2321 · Accepted Answer · 2017-05-12 13:05:32Z

1

Without being sure I have correctly understood the question, you could try the following:

require(data.table)
require(ggplot2)

dat1 <- fread('J  S1  S2  S3  S4  Z
              1   4   5   3   2  0
              2  12  11  34  44  0
              3  12  15  22  21  1
              4  10   9  10  11  1')

temp <- melt(dat1, id.vars = c("J", "Z"))

ggplot(temp, aes(x = J, y = value, color = variable, shape = as.factor(Z))) +
  geom_point()

This gives you the following plot:

One limitation that this approach has is that I have assumed that Z is a variable with discrete values (and a small number of discrete values at that). If this is not the case you can map it to alpha perhaps.

answered May 12, 2017 at 13:05

User2321

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5 Comments

pyring Over a year ago

Thanks for the answer. I'm gonna try this. But my data file is much more heavy, so... is there any way to do something similar but from the csv file? I mean, not from a table.

User2321 Over a year ago

No R loads everything in memory. So you will have to read the CSV file and store it in a data table / data frame...

User2321 Over a year ago

That being said, if you have a file that you can load in memory (as in you have enough RAM for it) data table and ggplot are quite efficient :)

pyring Over a year ago

What if I'd like to select only one level of Z. I mean, if I'd like to represent only data points for Z=0?

User2321 Over a year ago

Well you can subset your plot dataset for example temp_new = temp[Z==0]

Grant Winney · Accepted Answer · 2018-07-25 02:22:08Z

I ever so slightly "extended" the very helpful example above to read a CSV format data file (above) that is entitled 'exampledata.csv' and it looks like the following:

J,S1,S2,S3,S4,Z
1,4,5,3,2,0
2,12,11,34,44,0
3,12,15,22,21,1
4,10,9,10,11,1

To generate the very same plot that reads this CSV file, I used the following:

require(data.table)
require(ggplot2)
dat1 <- read.csv(file = "exampledata.csv")
temp <- melt(dat1, id.vars = c("J", "Z"))
ggplot(temp, aes(x = J, y = value, color = variable, shape = as.factor(Z))) +
geom_point(size = 3)

PS - I admittedly made the data points a bit larger because the eyes aren't as great as they used to be...

If you wish to use more data to create a bit more interesting plot, please use the following longer version of the CSV data file that is entitled 'exampledata.csv' (above):

J,S1,S2,S3,S4,Z
1,9,12,13,15,0
2,12,11,18,24,0
3,12,15,22,21,1
4,10,9,10,11,1
5,15,11,14,17,0
6,11,8,12,14,0
7,13,10,19,15,0
8,11,14,15,17,1
9,16,17,14,12,0
10,13,11,14,12,1

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