export csv rows where duplicate values found in column

Question

I have a csv file where I am trying to export rows into another csv file only where the values in the id column have duplicates.

I have the following csv file...

"id","blablah"
"valOne","valTwo"
"valOne","asdfdsa"
"valThree","valFour"
"valFive","valSix"
"valFive","qwreweq"
"valSeven","valEight"

I need the output csv file to look like the following...

"valOne","valTwo"
"valOne","asdfdsa"
"valFive","valSix"
"valFive","qwreweq"

Here is the code I have so far:

$inputCsv = Import-CSV './test.csv' -delimiter ","
#$output = @()
$inputCsv | Group-Object -prop id, blablah | Where-Object {$_.id -gt 1} |
    Select-Object
        #@{n='id';e={$_.Group[0].id}},
                  #@{n='blablah';e={$_.Group[0].blablah}}
    #Export-Csv 'C:\scripts\powershell\output.csv' -NoTypeInformation
#Write-Host $output
#$output | Export-Csv 'C:\scripts\powershell\output.csv' -NoTypeInformation

I've searched multiple how-to's but can't seem to find the write syntax. Can anyone help with this?

Doug Maurer · Accepted Answer · 2020-11-05 15:25:48Z

2

Just group on the ID property and if there is more than 1 count in the group then expand those and export.

$inputCsv = Import-CSV './test.csv' -delimiter ","

$inputCsv |
    Group-Object -Property ID |
        Where-Object count -gt 1 |
            Select-Object -ExpandProperty group |
                Export-Csv output.csv -NoTypeInformation

output.csv will contain

"id","blablah"
"valOne","valTwo"
"valOne","asdfdsa"
"valFive","valSix"
"valFive","qwreweq"

answered Nov 5, 2020 at 15:25

Doug Maurer

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1 Comment

Fiddle Freak Over a year ago

Thank you! The Select-Object -ExpandProperty group was the magic I was missing.

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