Using Powershell, how can i count the occurrence of each element in an array?

Question

If I have an array:

1 1 1 2 2 3 4 4 4 4 5 5

How can I use Powershell to tell me how many of each element there are in that array?

To be a little more clear, I should have a separate count for each array element:

Element:Count

1:3

2:2

3:1

4:4

5:2

Answer 1

You can use the Group-Object cmdlet:

PS> 1,1,1,2,2,3,4,4,4,4,5,5 | group

Count Name                      Group
----- ----                      -----
    3 1                         {1, 1, 1}
    2 2                         {2, 2}
    1 3                         {3}
    4 4                         {4, 4, 4, 4}
    2 5                         {5, 5}

If you want a hashtable for the items and their counts you just need a little ForEach-Object after it:

$array | group | % { $h = @{} } { $h[$_.Name] = $_.Count } { $h }

Answer 2

You can adjust the output and format it as you like:

PS> $ht= 1,1,1,2,2,3,4,4,4,4,5,5 | Group-Object -AsHashTable -AsString
PS> $ht

Name                           Value
----                           -----
2                              {2, 2}
4                              {4, 4, 4, 4}
5                              {5, 5}
1                              {1, 1, 1}
3                              {3}


PS> $ht['1']
1
1
1