PowerShell function that helps getting unique objects by one or multiple properties. Similar to Sort-Object -Unique but without any sorting and a bit faster.
| Parameter | Description |
|---|---|
InputObject |
The function is intended to work taking input from pipeline, this parameter bounds from pipeline and should not be used manually. |
On |
Property names used to filter for unique values on the objects. This parameter allows wildcards. See PSMemberInfoCollection<T>.Match Method. |
CaseSensitive |
Specifies if the filtering should be case sensitive when this switch is activated. |
Select |
Similar usage as Select-Object. Allows the use of calculated properties. |
- Get unique processes on
ProcessNameproperty:
Get-Process | Select-Unique -On ProcessName- Get unique processes on
ProcessNameandIdproperties:
Get-Process | Select-Unique -On ProcessName, Id- Get unique processes on any property starting with
ProcessandIdproperty:
Get-Process | Select-Unique -On Process*, Id- Get unique processes on
ProcessNameproperty and select propertyProcessNameasName:
Note: for calculated properties, the hashtable Keys will be the new property name and the Value can be a string representing the original object property name or a expression (ScriptBlock). The example after this one demonstrates the use of a ScriptBlock in a calculated property.
Get-Process | Select-Unique -On ProcessName -Select @{ Name = 'ProcessName' }- Get unique processes on
Idproperty and select propertyProcessNameasNameand propertyWorkingSet64using a calculated expression to convert the values from bytes to megabytes:
Get-Process | Select-Unique -On Id -Select @(
@{ Name = 'ProcessName' }
@{ MemoryUsage = { [string]::Format('{0:N0} Mb', ($_.WorkingSet64 / 1Mb)) }}
)-CaseSensitivefiltering:
$test = @(
[pscustomobject]@{ foo = 'Hello'; bar = 'World' }
[pscustomobject]@{ foo = 'Hello'; bar = 'World' }
[pscustomobject]@{ foo = 'Hello'; bar = 'WORLD' }
[pscustomobject]@{ foo = 'Hello'; bar = 'WORLD' }
[pscustomobject]@{ foo = 'HELLO'; bar = 'WORLD' }
[pscustomobject]@{ foo = 'HELLO'; bar = 'WORLD' }
)
$test | Select-Unique -On * -CaseSensitive
foo bar
--- ---
Hello World
Hello WORLD
HELLO WORLD
$test | Select-Unique -On *
foo bar
--- ---
Hello WorldBelow is a performance comparison between Sort-Object -Unique and this function on 3 properties. Source code for the performance tests in perftests.ps1.
Test Average RelativeSpeed
---- ------- -------------
Select-Unique 2474.40 1x
Sort-Object -Unique 3046.13 1.23xTestRun Test TotalMilliseconds
------- ---- -----------------
2 Select-Unique 2327.17
7 Select-Unique 2344.63
6 Select-Unique 2346.56
5 Select-Unique 2371.46
8 Select-Unique 2437.54
10 Select-Unique 2552.35
4 Select-Unique 2575.18
1 Select-Unique 2578.40
3 Select-Unique 2588.34
9 Select-Unique 2622.40
8 Sort-Object -Unique 2694.80
5 Sort-Object -Unique 2774.94
3 Sort-Object -Unique 2783.88
2 Sort-Object -Unique 2807.91
7 Sort-Object -Unique 2825.35
6 Sort-Object -Unique 2826.13
10 Sort-Object -Unique 2905.93
4 Sort-Object -Unique 3065.95
9 Sort-Object -Unique 3259.83
1 Sort-Object -Unique 4516.62
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent