Basic Set Operations

Introduction#

A set is a collection of items which can be anything. Whatever operator we need to work on these sets are in short the set operators and the operation is also known as set operation. Basic set operation includes Union, Intersection as well as addition, subtraction, etc.

Syntax#

• Group-Object

• Group-Object -Property <propertyName>

• Group-Object -Property <propertyName>, <propertyName2>

• Group-Object -Property <propertyName> -CaseSensitive

• Group-Object -Property <propertyName> -Culture <culture>

• Group-Object -Property <ScriptBlock>

• Sort-Object

• Sort-Object -Property <propertyName>

• Sort-Object -Property <ScriptBlock>

• Sort-Object -Property <propertyName>, <propertyName2>

• Sort-Object -Property <propertyObject> -CaseSensitive

• Sort-Object -Property <propertyObject> -Descending

• Sort-Object -Property <propertyObject> -Unique

• Sort-Object -Property <propertyObject> -Culture <culture>

Filtering: Where-Object / where / ?

Filter an enumeration by using a conditional expression

Synonyms:

Where-Object
where
?

Example:

$names = @( "Aaron", "Albert", "Alphonse","Bernie", "Charlie", "Danny", "Ernie", "Frank")

$names | Where-Object { $_ -like "A*" }
$names | where { $_ -like "A*" }
$names | ? { $_ -like "A*" }

Returns:

Aaron
Albert
Alphonse

Ordering: Sort-Object / sort

Sort an enumeration in either ascending or descending order

Synonyms:

Sort-Object
sort

Assuming:

$names = @( "Aaron", "Aaron", "Bernie", "Charlie", "Danny" )

Ascending sort is the default:

$names | Sort-Object
$names | sort

Aaron
Aaron
Bernie
Charlie
Danny

To request descending order:

$names | Sort-Object -Descending
$names | sort -Descending

Danny
Charlie
Bernie
Aaron
Aaron

You can sort using an expression.

$names | Sort-Object { $_.length }

Aaron
Aaron
Danny
Bernie
Charlie

Grouping: Group-Object / group

You can group an enumeration based on an expression.

Synonyms:

Group-Object
group

Examples:

$names = @( "Aaron", "Albert", "Alphonse","Bernie", "Charlie", "Danny", "Ernie", "Frank")

$names | Group-Object -Property Length
$names | group -Property Length

Response:

Projecting: Select-Object / select

Projecting an enumeration allows you to extract specific members of each object, to extract all the details, or to compute values for each object

Synonyms:

Select-Object
select

Selecting a subset of the properties:

$dir = dir "C:\MyFolder"

$dir | Select-Object Name, FullName, Attributes
$dir | select Name, FullName, Attributes

Selecting the first element, and show all its properties:

$d | select -first 1 *