How to transpose a matrix with PowerShell using regex? - powershell

Question

To accomplish with powershell:
Original
Transposed
0 1 2 3a b c d# $ # %
0 a #1 b $2 c #3 d %
how can a magic number be used (some regex in practice) where each original row has a variable number of columns so that only when the keyword occurs does that initiate a transpose?
Assuming that the original matrix is nx2 so something like:
a 1
b 2
c 3
d 4
a 5
d 6
a 7
b 8
c 9
The resulting matrix may very well be sparse, but each occurrence of a would signify a new column of output.

Answer 1

To transpose Rows to column conversion of file with powershell:
(Note that there is nothing in the referral that shows how magic numbers should be used to accomplish this)
$Orginal = #'
0 1 2 3
a b c d
# $ # %
'#
$Transposed = [Collections.ObjectModel.Collection[Object]]::new()
$Lines = $Orginal -Split '\r?\n'
for ($y = 0; $y -lt $Lines.Count; $y++) {
$Items = $lines[$y] -Split '\s+'
for ($x = 0; $x -lt $Items.Count; $x++) {
if ($x -ge $Transposed.Count) { $Transposed.Add((,#() * $Lines.Count)) }
$Transposed[$x][$y] = $Items[$x]
}
}
$Transposed |Foreach-Object { "$_" }
0 a #
1 b $
2 c #
3 d %