How can I use an array key in a powershell loop?

Question

I am using PowerShell to read and loop through a CSV file in order to create a new file for each row of the CSV file. I need to use the header names as part of each new file.

For each row of the CSV, how can I loop through each column and output the key and value for each variable in the output of each new file?

For example, if Master.csv contains

a,b,c
1,2,3
4,5,6

I would like to output a file named file1.txt:

a=1
b=2
c=3

and a file named file2.txt:

a=4
b=5
c=6

Is there an advantage to converting the array into a hash table, and using something like $d.Keys?

I am trying the below, but cannot get the key:

Import-Csv "C:\Master.csv" | %{
    $CsvObject = $_
    Write-Output "Working with $($CsvObject.a)"
    $CsvObject | ForEach-Object { 
        Write-Output "Key = Value`n" 
    }
}

Lee_Dailey · Accepted Answer · 2019-03-21 23:54:13Z

4

this will do the job, it seems. [grin] it uses the hidden .PSObject property to iterate thru the properties of each object.

# fake reading in a CSV file
#    in real life, use Import-CSV
$Instuff = @'
a,b,c
1,2,3
4,5,6
'@ | ConvertFrom-Csv

$Counter = 1

foreach ($IS_Item in $Instuff)
    {
    $FileName = "$env:TEMP\HamletHub_File$Counter.txt"
    $TextLines = foreach ($Prop in $IS_Item.PSObject.Properties.Name)
        {
        '{0} = {1}' -f $Prop, $IS_Item.$Prop
        }

    Set-Content -LiteralPath $FileName -Value $TextLines

    $Counter ++
    }

HamletHub_File1.txt content ...

a = 1
b = 2
c = 3

answered Mar 21, 2019 at 23:54

Lee_Dailey

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6 Comments

hsimah Over a year ago

Depending on the size of the data set using Add-Content per iteration over the keys might reduce memory usage.

Lee_Dailey Over a year ago

@hsimah - wouldn't that make for MORE writes? writes are SLOW compared to the rest of the script ...

hsimah Over a year ago

It would make for more writes and it would slow it down. But if you are processing millions of rows in a massive CSV it might be necessary to make the tradeoff of speed.

Lee_Dailey Over a year ago

@hsimah - ah! that would make sense ... thank you for clarifying that! [grin]

HamletHub Over a year ago

Thanks, it is not a huge file, I will test the above

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