CODEWITHSUNDEEP
powershell
IanB
IanB

Reputation: 271

Identify all items in a list which exist more than once and list them all

I have a list in which several items are repeated. I need to identify those items and create a new list to include all the repeated items, but for every time they reoccur.

Here's the list:

apple
orange
pear
carrot
tomato
cucumber
apple
apple
apple
cucumber
tomato

Thats apple x4, tomato x2, cucumber x2 and the rest x1.

The desired new list would be:

apple
apple
apple
apple
tomato
tomato
cucumber
cucumber

This omits the ones that exist only once and lists the ones that exist more than once and every time they occur.

I have tried:

$Fruits = Get-Content -Path C:\temp\Fruits.txt

$Unique = $Fruits | Select-Object -Unique
$MoreThanOne = Compare-Object –referenceobject $Unique –differenceobject $Fruits | Select-Object -ExpandProperty inputobject

$MoreThanOne

This produces:

apple
apple
apple
cucumber
tomato

Which is one missing for each fruit.

Any thoughts please?

Upvotes: 2

Views: 1062

Answers (1)

Paxz
Paxz

Reputation: 3046

By Comparing the both Objects and saving the difference you basically do a ($Unique - "each entry once"). This is because you want the difference between the variable which holds all entries and the variable which holds each entry once.

A better solution to this offers Group-Object. This groups all entries together so that you can look out for the one with multiple entries.

The Command Get-Content -Path C:\temp\Fruits.txt | Group-Object outputs this:

Count Name                      Group
----- ----                      -----
    4 apple                     {apple, apple, apple, apple}
    2 tomato                    {tomato, tomato}
    2 cucumber                  {cucumber, cucumber}
    1 carrot                    {carrot}
    1 pear                      {pear}
    1 orange                    {orange}

If you now filter correct:

Get-Content -Path C:\temp\Fruits.txt | Group-Object | Where-Object {$_.Count -gt 1} | Select-Object -ExpandProperty Group

The Output is this:

apple
apple
apple
apple
tomato
tomato
cucumber
cucumber

Upvotes: 8

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