How to use Group-Object on the first two columns (a, b) and (c, e) of the following array?
$a = @('a','b','x',10),
@('a','b','y',20),
@('c','e','x',50),
@('c','e','y',30)
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1 Answer
Group-Object accepts anonymous calculated properties, in place of property names:
PS C:\> $a | Group-Object @{ Expression={$_[0]} },@{ Expression = {$_[1]} }
It also accepts a ScriptBlock:
PS C:\> $a | Group-Object {$_[0]},{$_[1]}
As long as the expression can be evaluated to a string:
PS C:\> Get-Help Group-Object -Parameter Property
-Property [<Object[]>]
Specifies the properties for grouping. The objects are arranged into groups
based on the value of the specified property.
The value of the Property parameter can be a new calculated property.
To create a calculated, property, create a hash table with an Expression key
that specifies a string or script block value.
answered Sep 17, 2015 at 22:38
Mathias R. Jessen
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4 Comments
Fredrick
Just a note that anonymous is key here. If you supply a label with a hash it does nothing. ie @(1,2,3) | group-object @{l='mod';e={$_ % 2 -eq 0}} does nothing but removing l='mod' will work.
Mathias R. Jessen
@Fredrick What version of PowerShell are you using? In 5.1 and up, it's correctly validated and a
DictionaryKeyIllegal error is thrownFredrick
@MathiasRJessen I see. I get the exception with 7.0.0-preview.4 but not 7.0.0-preview.2.
Mathias R. Jessen
@Fredrick interesting. Might be a temporary regression in between, I haven't been keeping a close eye on changes to the utility cmdlets lately