Seeking balanced combination of fast, terse, and legible code to add up values from an array of objects - powershell

Question

Given the following array of objects:
Email Domain Tally
----- ----- -----
email1#domainA.com domainA.com 4
email1#domainB.com domainB.com 1
email2#domainC.com domainC.com 6
email4#domainA.com domainA.com 1
I'd like to "group by" Domain and add up Tally as I go. The end result would like this:
Domain Tally
------ -----
domainA.com 5
domainB.com 1
domainC.com 6
I have something that works but I feel like it's overly complicated.
$AllTheAddresses = Get-AllTheAddresses
$DomainTally = #()
foreach ($Addy in $AllTheAddresses)
{
if ($DomainTally | Where-Object {$_.RecipientDomain -eq $Addy.RecipientDomain})
{
$DomainTally |
Where-Object {$_.RecipientDomain -eq $Addy.RecipientDomain} |
ForEach-Object {$_.Tally += $Addy.Tally }
}
else
{
$props = #{
RecipientDomain = $Addy.RecipientDomain
Tally = $Addy.Tally
}
$DomainTally += New-Object -TypeName PSObject -Property $props
}
}

Answer 1

In my example, I'm creating the addresses as hashtables, but PowerShell will let you refer to the keys by .Property similar to an object.
If you're truly just summing by the Domain, then it seems like you don't need anything more complicated than a HashTable to create your running total.
The basic summation:
$Tally = #{}
$AllTheAddresses | ForEach-Object {
$Tally[$_.Domain] += $_.Tally
}
Using this sample data...
$AllTheAddresses = #(
#{ Email = "email1#domainA.com"; Domain = "domainA.com"; Tally = 4 };
#{ Email = "email1#domainB.com"; Domain = "domainB.com"; Tally = 1 };
#{ Email = "email1#domainC.com"; Domain = "domainC.com"; Tally = 6 };
#{ Email = "email1#domainA.com"; Domain = "domainA.com"; Tally = 1 }
)
And you get this output:
PS> $tally
Name Value
---- -----
domainC.com 6
domainB.com 1
domainA.com 5

Answer 2

Here is a "PowerShellic" version, notice the piping and flow of the data.
You could of course write this as a one liner (I did originally before I posted the answer here). The 'better' part of this is using the Group-Object and Measure-Object cmdlets. Notice there are no conditionals, again because the example uses the pipeline.
$AllTheAddresses |
Group-Object -Property Domain |
ForEach-Object {
$_ |
Tee-Object -Variable Domain |
Select-Object -Expand Group |
Measure-Object -Sum Tally |
Select-Object -Expand Sum |
ForEach-Object {
New-Object -TypeName PSObject -Property #{
'Domain' = $Domain.Name
'Tally' = $_
}
} |
Select-Object Domain, Tally
}
A more terse version
$AllTheAddresses |
Group Domain |
% {
$_ |
Tee-Object -Variable Domain |
Select -Expand Group |
Measure -Sum Tally |
Select -Expand Sum |
% {
New-Object PSObject -Property #{
'Domain' = $Domain.Name
'Tally' = $_
}
} |
Select Domain, Tally
}

Answer 3

Group-Object is definitely the way to go.
In the interest of terseness:
Get-AllTheAddresses |Group-Object Domain |Select-Object #{N='Domain';E={$_.Name}},#{N='Tally';E={($_.Group.Tally |Measure-Object).Sum}}