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Re: Testing object arrays using Compare-Object and -contains
Alex K. Angelopoulos [MVP] wrote:
> I'm having trouble finding a simple scheme for getting all objects
> which are members of a set B but not also members of another set A.
> I also checked into using Compare-Object. I like the way it works in
> terms of the thinking behind it, but it takes some low-level unboxing
> to work right. The shorthand is pretty lengthy:
>
> diff (gsnp) (gsnp -r) | ?{$_.SideIndicator -eq "=>"} | %{
> $_.InputObject} | asnp
Here is another approach:
$a=@(gsnp | ?{ !$_.isdefault }); $a+=@(gsnp -r)
$a | group name | ?{ $_.count -eq 1} | asnp
> Compare-Object also takes a while to run; this is not really the kind
> of thing it was specifically designed to do.
In my testing Get-PSSnapin without -r is the slow one:
[~] (measure-command { get-pssnapin }).milliseconds
714
[~] (measure-command { get-pssnapin -r}).milliseconds
7
....Compare-Object on the other hand is quite fast:
[~] $a = 1..500; $b = 5..505
[~] (measure-command { compare-object $a $b }).milliseconds
61
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