Powershell: Create multiple PSCustomObjects from 3 arrays with different length

Question

It is a beginner question but after hours of hours trying, i still do not know, what is better than create 3 different forloops, or one with if-decisions:

Example Code:

$a = 1,2,3
$b = 5,6,7,8,9
$c = 4, 10

$test = [PSCustomObject]@{
    A = $a
    B = $b
    C = $c
}

$test

I get output:

A         B               C      
-         -               -      
{1, 2, 3} {5, 6, 7, 8...} {4, 10}

I try with this easy example, what is best to export a csv-file with a header for each column(like above) but with values not in one line as here.So i get a headered table of all 1000+ values in the real problem. An extra file for each column seems also not the best solution..

I'm searching for a version to get output like(but for all data):

A,B,C
1,5,4
2,6,10
3,7,
,8,
...

I can get this when i iterate through the input and create a PSCustomObject for each line, but when i think of the different length i think of 3 loops. Of one loop with some extra-code to avoid Index-Errors. Something always tells me, that this is an easy task, but i can't find an elegant solution.

I appreciate every idea!

Thank you

for loop definitely works for this, you only need one not three. but foreach and while and do will work too it just depends on which one you like more. what you're attempting to do is called join arrays or merge arrays. — Santiago Squarzon
– Santiago Squarzon, Commented Dec 11, 2021 at 18:12

Santiago Squarzon · Accepted Answer · 2021-12-11 18:37:04Z

2

Here is one way of doing this using a while loop and Measure-Object to get the maximum count of elements on the 3 arrays:

$a = 1,2,3
$b = 5,6,7,8,9
$c = 4,10

$max = $a.Count, $b.Count, $c.Count | Measure-Object -Maximum
$i = 0

$result = while($max.Maximum--)
{
    [pscustomobject]@{
        A = $a[$i]
        B = $b[$i]
        C = $c[$i]
    }
    $i++
}

Now looking at your expected output, seems like you want to export the data to a CSV, in that case you would use Export-Csv, if you just want to have the data converted but without exporting it you can use ConvertTo-Csv:

PS /> $result | ConvertTo-Csv -NoTypeInformation

"A","B","C"
"1","5","4"
"2","6","10"
"3","7",
,"8",
,"9",

answered Dec 11, 2021 at 18:37

Santiago Squarzon

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3 Comments

Andy W. Over a year ago

Thank you so much! Pretty cool, and today i nearly got crazy to figure it out myself. I didn't try anything similiar, because i didn't ´know before, that accessing an array in Powershell returns $null, when out of index. Like it would in other programming languages. Well, thank you again! Very nice!!!!

Santiago Squarzon Over a year ago

@AndyW. well, if you use StrictMode it will throw with an out of bound exception but this turned off by default. Please consider accepting the answer if it could solve your problem.

Santiago Squarzon Over a year ago

@AndyW. thank you, note that using StrictMode the code would be more complex however it is helpful when debugging code but it is a matter of personal preference. I personally had never have a need to turn it on.

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