Convert classic users to claims using PowerShell

# START INITIALISATIONS
Add-PSSnapin Microsoft.SharePoint.PowerShell -erroraction SilentlyContinue
#Initialise Web
$web = Get-SPWeb -identity "site collection URL"
#Initialise Sharepoint list
$list = $web.Lists["Site Owner Survey Input Form"]    
write-host $web
write-host $list

#Initialise AD
$_Searcher= New-Object System.DirectoryServices.DirectorySearcher
$_Searcher.PageSize = 1000

# END INITIALISATIONS

# START Main Code

$filepath = "D:\MyInput.csv"
Import-CSV $filepath | foreach-object{
$siteurl = $_.siteurl
$landid = $_.lanid
$sameaccountname = $landid
write-host $siteurl
write-host $landid
write-host $sameaccountname
 
$claim = "i:0ǵ.t|federation.global.xyz.com|" + $sameaccountname
$cp = New-SPClaimsPrincipal -Identity $claim -IdentityType "EncodedClaim"
$user = $web.EnsureUser($cp.ToEncodedString())
                   
$newItem = $list.Items.Add()
$newItem["Title"] = $siteurl;
$newItem["Primary Owner"] = $user;
$newItem.Update();

}