Create csv file with Hashmap in Kotlin-CodePudding

I am fairly new to kotlin, and have wanted to change the way to save my CSV file. Currently my Hashmap is :

private var Sdata:MutableMap<String, MutableList<String>> = mutableMapOf<String, MutableList<String>>()

and my data looks like this :

{a1 = [1:2:3:4, 1:2:3:4, ....], b2 = [1:2:3:4, 1:2:3:4,....]}

and my csv saving function:

binding.btnSave.setOnClickListener() {
        Sdata = viewModel.savehash
        Log.d(TAG, "CSV VIEW: ${Sdata.keys}")
        Log.d(TAG, "CSV VIEW: ${Sdata.values.size}")
        if(Sdata.keys.size != 0) {
            val csv = File(this.filesDir, "test1.csv") // Internal App storage

            val valuesSeparator = ","
            val lineTerminator = "\r\n"
            //write header, overwrite file if it has existed
            csv.writeText(
                Sdata.keys.joinToString(
                    separator = valuesSeparator,
                    postfix = lineTerminator
                )
            )
            val nRows = Sdata.values.maxOf { it?.size }    // size of list ar not all equal
            for (i in 0 until nRows) {
                val row = Sdata.values
                    .map { it.getOrElse(i) { "" }.trim() }
                    .joinToString(separator = valuesSeparator, postfix = lineTerminator)
                csv.appendText(row)
            }

            Toast.makeText(this, "Data Saved to Documents", Toast.LENGTH_SHORT).show()
        }
        else{
            Toast.makeText(this, "No Logged Data", Toast.LENGTH_SHORT).show()
        }
    }

converts my files to look like this :

I want to reiterate column values where column a1 has --> a1W, a1X, a1Y, a1Z and the values underneath are separated by the ":" delimters so that each single column is separated into 4 columns. Will this be difficult in Kotlin? Any help would be greatly appreciated thankyou!!

CodePudding user response：

To do that, you just need to slightly modify the way you create the headers row and the data rows.

For the header row, change the Sdata.keys.joinToString(...) into:

Sdata.keys
    .flatMap { listOf("${it}W", "${it}X", "${it}Y", "${it}Z") }
    .joinToString(separator = valuesSeparator, postfix = lineTerminator)

The flatMap call allows you to create a new list by converting each element (like a1) into a list of 4 elements (a1W, a1X...) and joining all those lists together into a big one.

For the data row, change the .map { it.getOrElse(i) { "" }.trim() } into:

.flatMap { it.getOrElse(i) { "" }.trim().split(":") }

CodePudding user response：

The following for loop instead of yours should do the trick (thanks @Joffrey for the hint):

for (i in 0 until nRows) {
    val row = Sdata.flatMap { it.getOrElse(1) { "" }.trim().split(":") }
        .joinToString(separator = valuesSeparator, postfix = lineTerminator)
    csv.appendText(row)
}

Basically, you split your 1:2:3:4 values into a list containing the four numbers. And then your code should do the rest.