B4J Question How to save a mulitielement array as csv?

positrom2 · Dec 29, 2013

I am having an array a(n,199). For n=99, how to save it as a csv file so that I have 100 columns and 200 rows?
For n=3 for example, I can use

B4X:

For i=0 To 199
CSVlist.Add(Array As String(i,a(i,0),a(i,1),a(i,2),a(i,3)))
Next
su.SaveCSV("d:\",filename&".csv",",", CSVlist)

but for large n this becomes unhandy.
There is the hint that one could "add the array directly using Addall", but I can't figure it out.

stevel05 · Dec 29, 2013

To use add all you would need to be able to access the array with a single index to get a row, which is not possible.

You could build the string for each row before adding it.

Something like:

B4X:

    For i=0 To 199
        Dim LineStr As String = i&","
        For j = 0 To 99
            LineStr = LineStr & A(j,i)&","
        Next
        'Remove the last ","
        LineStr=LineStr.SubString2(0,LineStr.Length-1)
        CSVList.Add(LineStr)
    Next

You may want to enclose each item in quotes which is common practice and can save issues where the data string may contain a comma:

B4X:

    For i=0 To 199
        Dim LineStr As String = QUOTE&i&QUOTE&","
        For j = 0 To 99
            LineStr = LineStr & QUOTE&A(j,i)&QUOTE&","
        Next
        'Remove the last ","
        LineStr=LineStr.SubString2(0,LineStr.Length-1)
        CSVList.Add(LineStr)
    Next

Example attached

positrom2 · Dec 30, 2013

Hi Stevel,
thanks for your prompt answer, it works, (of course). But Stringutils to save as csv file did not like that LineStr list format, for whatever reason. However, I could use File.writelist(....,LineStr) directly.
Thanks.

stevel05 · Dec 30, 2013

Ok, just checked, SUtils requires a list of arrays. So the code would need to be something like:

B4X:

For i=0 To 199
        Dim B(101) As String
        B(0) = i
        For j = 1 To 100
            B(j) = A(j-1,i)
        Next
        CSVList.Add(B)
    Next

positrom2 · Dec 30, 2013

Yes, much more elegant (to me...). Thank you.

B4J Question How to save a mulitielement array as csv?

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B4J Question How to save a mulitielement array as csv?

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