Sorting Hash Tables

Over the weekend I received a nice comment from a reader who came across an old post of mine on turning an object into a hash table.  He wanted to add a comment but my blog closes comments after a period of time. But I thought it was worth sharing, especially for those of you still getting started with PowerShell. The comment was on how to sort a hash table.

Let's say you have a simple hash table like this:

$hash = @{
Name="Jeff"
Size = 123
Color = "Green"
Computer = "Yoga2Pro"
}

And is displayed like this:

PS C:\scripts> $hash

Name                           Value
----                           -----
Color                          Green
Name                           Jeff
Computer                       Yoga2Pro
Size                           123

To sort on the keys, you can use the GetEnumerator() method which is part of every hash table object. This method creates a System.Collections.DictionaryEntry object for each item in the hash table.

PS C:\scripts> $hash.GetEnumerator()  | get-member


   TypeName: System.Collections.DictionaryEntry

Name        MemberType    Definition
----        ----------    ----------
Name        AliasProperty Name = Key
Equals      Method        bool Equals(System.Object obj)
GetHashCode Method        int GetHashCode()
GetType     Method        type GetType()
ToString    Method        string ToString()
Key         Property      System.Object Key {get;set;}
Value       Property      System.Object Value {get;set;}

This means you can sort on any property.

PS C:\scripts> $hash.GetEnumerator() | sort key

Name                           Value
----                           -----
Color                          Green
Computer                       Yoga2Pro
Name                           Jeff
Size                           123


PS C:\scripts> $hash.GetEnumerator() | sort value

Name                           Value
----                           -----
Size                           123
Color                          Green
Name                           Jeff
Computer                       Yoga2Pro

By the way, starting in PowerShell 3.0, you could "pre-sort" the hash table by defining it as 'ordered'.

$hash = [ordered]@{
Name="Jeff"
Computer = "Yoga2Pro"
Color = "Green"
Size = 123
}

Now the hash table will always be sorted in the order you defined the entries.

PS C:\scripts> $hash

Name                           Value
----                           -----
Name                           Jeff
Computer                       Yoga2Pro
Color                          Green
Size                           123

Although, if you want to sort you still can.

PS C:\scripts> $hash.GetEnumerator() | sort name -Descending

Name                           Value
----                           -----
Size                           123
Name                           Jeff
Computer                       Yoga2Pro
Color                          Green

Have a great week and I hope you get things sorted out.

---

---