Write a free style header area

[hantsy]

In our project, there is a case we want to export data to CSV like this.

We want to add some statistic data in the header area, then add a collection of data.

For the latter, it is easy to do via DataSchema and exporting to CSV file format, but what is the best way to append the first part?

[koperagen]

Hi! As an idea:

val content = buildString { 
  appendLine("NAME,$name")
  appendLine("TOTAL,${df.count()}")
  append(df.toCsvStr())
}

File("output").writeText(content)

[Jolanrensen]

@koperagen's solution will produce what you expect indeed :) However, I do need to mention that putting data like that in the header does not produce valid CSV. It will be difficult to read it with another program unless it has a skipLines/readLines option like DataFrame, as CSV is expected to have columnar data only.

However, there is the possibility to specify headerComments: List<String> when writing to CSV. It may be a good idea to put the NAME and TOTAL there to keep your file valid CSV.