Simple PivotTable in Powershell

gistfile1.ps1

function Invoke-Pivot {

    param (
        $data,
        [string]$rotate, # Bits along the top
        [string]$keep, # Those along the side
        [string]$value # What to total
    )

    # Create variable to store the output
    $NewRows = @()

    # Fields of interest
    # $rotate = "Activity" # Bits along the top
    # $keep = "Category" # Those along the side
    # $value = "Duration" # What to total

    # Find the unique "Rotate" [top row of the pivot] values and sort ascending
    $pivots = $data | select -unique $rotate | foreach { $_.$rotate} | Sort-Object

    # Step through the original data...
    #  for each of the "Keep" [left hand side] find the Sum of the "Value" for each "Rotate"

    $data | 
        group $keep | 
        foreach { 
            $group = $_.Group 
            # Create the data row and name it as per the "Keep"
            $row = new-object psobject
            $row | add-member NoteProperty $keep $_.Name 
            
            foreach ($pivot in $pivots) { # Cycle through the unique "Rotate" values and get the sum
                $row | add-member NoteProperty $pivot ($group | where { $_.$rotate -eq $pivot } | measure -sum $value).Sum
            }

            # Add the total to the row
            $row | add-member NoteProperty Total ($group | measure -sum $value).Sum

            # Add the row to the collection 
            $NewRows += $row
        } 

    # Do something with the pivot rows
    return $NewRows

<#
.SYNOPSIS
    Transforms rows and columns of a PSObject or other named object.

.DESCRIPTION
    Long description

.EXAMPLE
    PS C:\> <example usage>
    Explanation of what the example does

.INPUTS
    Inputs (if any)

.OUTPUTS
    Output (if any)

.NOTES
    #############################################################################
    Rotates a vertical set similar to an Excel PivotTable 

    Given $data in the format: 

    Category     Activity     Duration 
    ------------ ------------ -------- 
    Management   Email        1 
    Management   Slides       4 
    Project A    Email        2 
    Project A    Research     1 
    Project B    Research     3 

    with $keep = "Category", $rotate = "Activity", $value = "Duration" 

    Return 

    Category   Email Slides Total 
    ---------- ----- ------ -----
    Management     1      4     5
    Project A      2      1     3
    Project B      3            3

    #############################################################################
    Changes
    ========# 
    Who          When       Details
    ------------ ---------- -----------------------------------------------
    dennis      2019-10-22  Converted to advanced script
    
    aphalon      2015-07-23 1. Added $NewRows variable to hold the output
                            2. Unique values were hardcoded for the example
                            -> changed to be the variable fields
                            3. Sorted $pivots 
                            4. Added a Total column
                            5. Commented it a little :)
    #############################################################################
#>
}