Reading a CSV with data.table::read fails claiming the file is empty

[James Collier]

Here is a reproduction:

webr::install("data.table")
chisq <- data.frame(A = c(1, 0.5, 0.2),
                    B = c(0.1, 0.2, 0.3),
                    C = c(0.54, 0.1, 0.05))
print(chisq)
data.table::fwrite(chisq, file = "chisq.csv", col.names=FALSE)
readLines("chisq.csv")
data.table::fread("chisq.csv")

I expect to read the CSV with data.table::fread. On desktop I get this output:

$ $ Rscript reprod.R 
    A   B    C
1 1.0 0.1 0.54
2 0.5 0.2 0.10
3 0.2 0.3 0.05
[1] "1,0.1,0.54"   "0.5,0.2,0.1"  "0.2,0.3,0.05"
      V1    V2    V3
   <num> <num> <num>
1:   1.0   0.1  0.54
2:   0.5   0.2  0.10
3:   0.2   0.3  0.05

In WebR I get this output:

[1] "test"
    A   B    C
1 1.0 0.1 0.54
2 0.5 0.2 0.10
3 0.2 0.3 0.05
[1] "1,0.1,0.54"   "0.5,0.2,0.1"  "0.2,0.3,0.05"
Error: File is empty: chisq.csv

[James Collier]

This looks like a potential culprit?

[George Stagg]

This is related to Rdatatable/data.table#5969

I tested a new build of the package on a pre-release version of webR 0.3.0 and it is working there:

So I am confident that once webR 0.3.0 is released and the default webR package repo is updated, the problem should go away. Unfortunately, the package repo is frozen in preparation for release, so I will leave this issue open until then.

[George Stagg]

This now seems to be fixed in both https://webr.r-wasm.org/latest/ and https://webr.r-wasm.org/v0.3.1/.