PowerShell - Dynamically Combine CSV Columns

Question

I have a CSV file that I'm restructuring using PowerShell and I want to combine values across a number of fields that have names matched using a wildcard. I am already selecting my CSV fields as I import them, so would like to use something akin to the following :

$c4 = @{n="Grouped";e={$_.C1+$_.C2+$_.C3}}

$csv = import-csv $incsv | select $c4

This works, but I am trying to find a way of dynamically creating the e expression in $c4 . I am able to build an array of column names (in this example, to include C1 to C3), but can't figure out how to build the expression using this.

I have a couple of limitations:

• I'm stuck with V2 and am unable to upgrade the version of PowerShell being used
• The final CSV files are very large, so the solution needs to take this into account

Any help is greatly appreciated!

Thanks.

Answer 1

You can create a scriptblock from a string that you've composed from your field names eg:

$sb = [scriptblock]::create("`$_.C1+`$_.C2+`$_.C3")
$c4 = @{n="Grouped";e=$sb}

With a string you can use looping and various constructs to create your string and then pass that to [scriptblock]::create() to get back a scriptblock that you can use for the Expression part of the Select hashtable.