Modify/transform data in Select-Object

Question

Say I've got a list of items. I'd like to export to csv, but I want to do some calculations / modifications before I do so.

Basically, the setup looks like this:

PS C:\Files> gci
Directory: C:\Files

Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        10/23/2014   6:03 PM      11084 Blob.txt
-a---        10/13/2014   1:32 PM      31591 dates.txt
-a---         2/11/2014   1:46 PM      11990 out.txt

PS C:\Files> $data = gci

And I can select the items I want to put into CSV easily enough. The actual Export-CSV part is omitted for brevity

PS C:\Files> $data | Select-Object FullName,name

But what I REALLY want to do is calculate a few columns and also include those in the CSV. Just as an example, say I want to count the '\' characters to get an idea of the folder depth. I think you can tell what I am trying here, even though it errors out.

PS C:\Files> $data | Select-Object FullName,name,FullName.Split('\').Count
Select-Object : A positional parameter cannot be found that accepts argument '1'.    

Is there a way to get this to work?

Answer 1

What you need is a calculated property (thank you Ansgar Wiechers for correcting my terminology and providing a link) to do that for you. You can accomplish this in a Select command by creating a kind of impromptu hashtable like so:

PS C:\Files> $data | Select-Object FullName,name,@{name='FolderDepth';expression= {$_.FullName.Split('\').Count}}

That could be shortened to @{n='Name';e={scriptblock}} where n stands for name, and is interchangeable with l (short for label). e is short for expression.

Answer 2

Yes. What you are looking for is more complex Select-Object statement using calculated property. Sample syntax:

@{Label = "Calculation";Expression ={$_.FullName.Split('\').Count}}

Then you insert this into a select statement, usually with other variables.

$data | Select-Object FullName,name,@{Label = "TheCount";Expression ={$_.FullName.Split('\').Count}}