Integrating raster images in a scatter plot via R

Question

I'm trying to plot a graph of a linear profile with integrated pictures of drilling cores at certain points and hights in the profile. I have a directory with 22 .png images of the drilling cores, each has a length of 1 m, and a .csv file with the x and z (z_korrig in .csv file) positions of the top center of each image. Since I'm a novice when it comes to R, I'm stuck at the point where I assign the coordinates to the raster images and actually integrate them into the plot.

Here is my code so far with the output scatter plot:

#import coordinates
coord <- read.csv("Bohrungen Höhe.csv", sep = ";", header = TRUE)

#plot to check csv
plot(coord$x, coord$z_korrig, 
     xlab = "length in m",
     ylab = "heigth in m",
     main = "profile 1")

The raster images should be positioned with their top center at the points in the scatter plot (images have the names B01.png..., corresponding to the ID with the coordinates in the .csv file), showing the actual profile. I also feel like it would be beneficial for visualisation to double the width of the images.

This is the content of my .csv file:

    ID   x    z z_korrig
1  B01 100 4.77     3.32
2  B02 110 4.83     3.38
3  B03 120 4.96     3.51
4  B04 130 5.28     3.83
5  B05  80 4.69     3.24
6  B06 140 5.69     4.24
7  B07 150 6.03     4.58
8  B08 160 6.25     4.80
9  B09 170 6.38     4.93
10 B10 180 6.48     5.03
11 B11 190 6.64     5.19
12 B12 200 6.82     5.37
13 B13 210 6.97     5.52
14 B14  70 4.81     3.36
15 B15  60 4.94     3.49
16 B16  50 5.05     3.60
17 B17  40 5.19     3.74
18 B18  30 5.33     3.88
19 B19  20 5.46     4.01
20 B20  10 5.82     4.37
21 B21   0 5.65     4.20
22 B22  90 4.72     3.27

EDIT: This is what I was hoping to achive:

Answer 1

I'll do an example for six images. Test data created like this:

set.seed(1234) # fix random numbers
d = data.frame(ID=paste0("B0",1:6))
d$x = sample(1:6) *10
d$z = runif(6, 4, 7)

> head(d)
   ID  x        z
1 B01 40 4.697652
2 B02 20 5.998251
3 B03 50 5.542753
4 B04 10 6.080774
5 B05 60 5.634925
6 B06 30 4.848201

Then assuming files B01.png to B06.png exist in the current directory, read them into a list object as arrays:

library(png)
ims = lapply(d$ID, function(ID){readPNG(paste0(ID,".png"))})
names(ims) <- d$ID

We want the images to be this many units wide and this many units high, on the scale of the data:

w = 4
h = 1

Our plot needs a bit of extra width either side of the data points:

xmin = min(d$x) - w
xmax = max(d$x) + w

And needs to extend above the images. At this point I realise I've put the images with their bottom on the data point, but I'll leave it as an exercise for you to change things so they align with the top.

ymin = min(d$z)
ymax = max(d$z) + h

Now I can set up a blank plot with that range:

plot(d$x, d$z, xlim=c(xmin, xmax), ylim=c(ymin, ymax), type="n")

And loop over the rows of the data putting the images down. You'll need to adjust this to get the images below the data point. Sorry, but working out how to do that might be insightful:

for(n in 1:nrow(d)){
    xl = d$x[n]-w/2
    yl = d$z[n]
    rasterImage(ims[[n]],
                xl, yl,
                xl+w, yl+h
                )
}

Which gives:

You could also add the text label you've got at the top of the image with the text function.