reconstructing path from outlined directory structure - powershell

Question

I have a csv file in the form:
Address,L0,L1,L2,L3,L4
01,Species,,,,
01.01,,Mammals,,,
01.01.01,,,Threatened,,
...
I want to use it to create a matching directory structure. I'm new to scripting and PowerShell, and in this case I'm not sure if I'm on totally the wrong track. Should I use a separate array to store each level's Name/Address pairs and then use those arrays like a lookup table to build the path? If so, I guess I'm stuck on how to set up if-thens based on a row's Address. This is as far as I've got so suggestions on general strategy or links to similar kinds of problem would be really welcome:
$folders = Import-Csv "E:\path\to\file.csv"
$folders | foreach {
$row = new-object PSObject -Property #{
Address = $_.Address;
Level = ([regex]::Matches($_.Address, "\." )).count;
L0 = $_.L0
L1 = $_.L1
L2 = $_.L2
L3 = $_.L3
}
$array += $row
}
#top level directories
$0 = $array | ?{$_.Level -eq 0} |
Select-Object #{n="Address";e={$_.Address;}},#{n="Name";e={$_.L0}}
#2nd level directories
$1 = $array | ?{$_.Level -eq 1} |
Select-Object #{n="Number";e={$_.Address.split(".")[-1];}},#{n="Name";e={$_.L1}}

Answer 1

Not tested, but I think this might do what you want:
$root = 'E:\SomeDirName'
Switch -Regex (Get-Content "E:\path\to\file.csv")
{
'^01,(\w+),,,,$' { $L1,$L2,$L3,$L4 = $null; $L0=$matches[1];mkdir "$root\$L0" }
'^01\.01,,(\w+),,,$' { $L1=$matches[1];mkdir "$root\$L0\$L1" }
'^01\.01\.01,,,(\w+),,$' { $L2=$matches[1];mkdir "$root\$L0\$L1\$L2" }
'^01\.01\.01\.01,,,,(\w+),$' { $L3=$matches[1];mkdir "$root\$L0\$L1\$L2\$L3" }
'^01\.01\.01\.01\.01,,,,,(\w+)$' { $L4=$matches[1];mkdir "$root\$L0\$L1\$L2\$L3\$L4" }
}

Answer 2

To solve that kind of problem a programming concept called recursion is often used.
In short a recursive function is a function that call itself.
I successfully tested this code with you CSV input:
$csvPath = 'C:\Temp\test.csv'
$folderRoot = 'C:\Temp'
$csv = Import-Csv $csvPath -Delimiter ',' | Sort-Object -Property Address
# Recursive function
function Recurse-Folder( $folderAddress, $basePath )
{
# Getting the list of current folder subfolders
$childFolders = $null
if( $folderAddress -like '' )
{
$childFolders = $csv | Where-Object { $_.Address -like '??' }
}
else
{
$childFolders = $csv | Where-Object { $_.Address -like $( $folderAddress + '.??' ) }
}
# For each child folder
foreach( $childFolder in $childFolders )
{
# Get the folder name
$dotCount = $childFolder.Address.Split('.').Count - 1
$childFolderName = $childFolder.$('L'+$dotCount)
if( $childFolderName -ne '')
{
$childFolderPath = $basePath + '\' + $childFolderName
# Creating child folder and calling recursive function for it
New-Item -Path $childFolderPath -ItemType Directory
Recurse-Folder $childFolder.Address $childFolderPath
}
}
}
Recurse-Folder '' $folderRoot