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, Dec 11 '21 at 18:12

score 2 · Accepted Answer · answered Dec 11 '21 at 18:37

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 '21 at 18:37

Santiago Squarzon

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1

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!!!! – Andy W. Dec 11 '21 at 19:04
1

@AndyW. well, if you use [`StrictMode`](https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/set-strictmode?view=powershell-7.2) it will throw with an out of bound exception but this turned off by default. Please consider [accepting](https://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work/5235#5235) the answer if it could solve your problem. – Santiago Squarzon Dec 11 '21 at 19:07
@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. – Santiago Squarzon Dec 11 '21 at 19:16

Powershell: Create multiple PSCustomObjects from 3 arrays with different length

1 Answers1