Question

I’m looking to transform all the files into Array[Array[String]]. The first dimension should be the row number. The second dimension should be the column number. So far I have

  for (file <- allFiles) {

    val split = for (line <- Source.fromFile(...) yield line.split(",")

  } yield split

But it doesn’t seem to be working. As a concrete example if I had

file1.csv

a,b,c
d,e,f

file2.csv

1,2,3

I would want as output

a,b,c
d,e,f
1,2,3

Answer 1

By doing this:

for (line <- Source.fromFile(...)) ...

You are iterating over each character from the file, not each line.

You probably meant:

for (line <- Source.fromFile(...).getLines) ...

By the way, you can combine your two for comprehensions into one:

scala> val allFiles = Array("data1.csv", "data2.csv")
allFiles: Array[java.lang.String] = Array(data1.csv, data2.csv)

scala> for {
     |   filename <- allFiles
     |   line <- io.Source.fromFile(filename).getLines
     | } yield line.split(",")
res3: Array[Array[java.lang.String]] = Array(Array(a, b, c), Array(d, e, f), Array(1, 2, 3))