Transpose a 2D record

[Ville Rantanen]

Ever had to iterate and collect data from a component that produces several outputs?   

You might have this kind of syntax:

orig={}
files={}
for x:std.range(1,200) {
    orig[x]=BashEvaluate(script="echo foo > @optOut1@; echo "+x+" >> @optOut1@;")
    files[x]=orig[x].optOut1
}
collectedFiles=Array2Folder(files,fileMode="@key@.txt")

Now, this may not look like an improvement, but often you don't want to collect several records in a for-loop:

First we need to create a function for the transpose:

function transpose(record a,record b)->() {
    for i,x,v:std.enumerate(a) { for y,u:v {
        if i==1 { b[y]={} } b[y][x]=u }}
    return {}
}

now we can formulate the for-loop with a single record:

orig={}
for x:std.range(1,200) {
    orig[x]=BashEvaluate(script="echo foo > @optOut1@; echo "+x+" >> @optOut1@;")
}  
files={}
transpose(a=orig,b=files)
collectedFiles=Array2Folder(files.optOut1,fileMode="@key@.txt")

In short, the orig record contains two levels of indexes: the first is running from 1 - 200, and the second are the output ports of the BashEvaluate component (optOut1-3, folder1-3, arrays ... etc)

After the transpose, the files  record has the same two levels, but in reversed order.