Hash tables

$hash = @{}
get-childitem $home -recurse |
foreach-object {$hash[$_.extension]++}
$hash

get-help -full about_hash_tables | less

#import hashtable
ConvertFrom-StringData

Object Types in HashTables

    The keys and values in a hash table can have any .NET object type,

    and a single hash table can have keys and values of multiple types.

$p = @{"PowerShell" = (get-process PowerShell);
    "Notepad" = (get-process notepad)}
$p = $p + @{(get-service winrm) = ((get-service winrm).status)}
$p
$p.keys

$SourcesHT = @{}
Foreach ($source in $SourcesTBL)
{
    $SourcesHT.Add($Source.id,$Source.Name)
}

Convert to Hashtable or pscustomobject

function ConvertTo-PsCustomObjectFromHashtable { 
     param ( 
         [Parameter(  
             Position = 0,   
             Mandatory = $true,   
             ValueFromPipeline = $true,  
             ValueFromPipelineByPropertyName = $true  
         )] [object[]]$hashtable 
     ); 
     
     begin { $i = 0; } 
     
     process { 
         foreach ($myHashtable in $hashtable) { 
             if ($myHashtable.GetType().Name -eq 'hashtable') { 
                 $output = New-Object -TypeName PsObject; 
                 Add-Member -InputObject $output -MemberType ScriptMethod -Name AddNote -Value {  
                     Add-Member -InputObject $this -MemberType NoteProperty -Name $args[0] -Value $args[1]; 
                 }; 
                 $myHashtable.Keys | Sort-Object | % {  
                     $output.AddNote($_, $myHashtable.$_);  
                 } 
                 $output; 
             } else { 
                 Write-Warning "Index $i is not of type [hashtable]"; 
             } 
             $i += 1;  
         } 
     } 
} 

function ConvertTo-HashtableFromPsCustomObject { 
     param ( 
         [Parameter(  
             Position = 0,   
             Mandatory = $true,   
             ValueFromPipeline = $true,  
             ValueFromPipelineByPropertyName = $true  
         )] [object[]]$psCustomObject 
     ); 
     
     process { 
         foreach ($myPsObject in $psCustomObject) { 
             $output = @{}; 
             $myPsObject | Get-Member -MemberType *Property | % { 
                 $output.($_.name) = $myPsObject.($_.name); 
             } 
             $output; 
         } 
     } 
}