Get Substring of value when using import-Csv in PowerShell - powershell

Question

I have a PowerShell script that imports a CSV file, filters out rows from two columns and then concatenates a string and exports to a new CSV file.
Import-Csv "redirect_and_canonical_chains.csv" |
Where { $_."Number of Redirects" -gt 1} |
Select {"Redirect 301 ",$_.Address, $_."Final Address"} |
Export-Csv "testing-export.csv" –NoTypeInformation
This all works fine however for the $_.Address value I want to strip the domain, sub-domain and protocol etc using the following regex
^(?:https?:\/\/)?(?:[^#\/\n]+#)?(?:www\.)?([^:\/\n]+)
This individually works and matches as I want but I am not sure of the best way to implement when selecting the data (should I use $match, -replace etc) or whether I should do it after importing?
Any advice greatly appreciated!
Many thanks
Mike

Answer 1

The best place to do it would be in the select clause, as in:
select Property1,Property2,#{name='NewProperty';expression={$_.Property3 -replace '<regex>',''}}
That's what a calculated property is: you give the name, and the way to create it.Your regex might need revision to work with PowerShell, though.

Answer 2

I've realized now that I can just use .Replace in the following way :)
Select {"Redirect 301 ",$_.Address.Replace('http://', 'testing'), $_."Final Address"}

Answer 3

Based on follow-up comments, the intent behind your Select[-Object] call was to create a single string with space-separated entries from each input object.
Note that use of Export-Csv then makes no sense, because it will create a single Length column with the input strings' length rather than output the strings themselves.
In a follow-up comment you posted a solution that used Write-Host to produce the output string, but Write-Host is generally the wrong tool to use, unless the intent is explicitly to write to the display only, thereby bypassing PowerShell's output streams and thus the ability to send the output to other commands, capture it in a variable or redirect it to a file.
Here's a fixed version of your command, which uses the -join operator to join the elements of a string array to output a single, space-separated string:
$sampleCsvInput = [pscustomobject] #{
Address = 'http://www.example.org/more/stuff';
'Final Address' = 'more/stuff2'
}
$sampleCsvInput | ForEach-Object {
"Redirect 301 ",
($_.Address -replace '^(?:https?://)?(?:[^#/\n]+#)?(?:www\.)?([^:/\n]+)', ''),
$_.'Final Address' -join ' '
}
Note that , - PowerShell's array-construction operator - has higher precedence than the -join operator, so the -join operation indeed joins all 3 preceding array elements.
The above yields the following string:
Redirect 301 /more/stuff more/stuff2