Finding an item of one array that matches a certain string of an item in another array

Question

Hello everyone, I humbly ask for help with one powershell issue that I cant solve. Its basically described in the title - I have two arrays containing a lot of items, and I need to find an item from array 1 that matches a certain string of characters in array 2. So far I tried something like this:

[array]$arr1 = 'charlie','echo','bravo','lima','zulu','alpha'
[array]$arr2 = 'eagle', 'horse', 'cat', 'goat', 'dog', 'charlie'
$arr1 | Where-Object {$arr2 -contains 'charlie'}

But this will only return all items from array1:

PS C:\Users\user\folder> $arr1 | Where-Object {$arr2 -contains 'charlie'}
charlie
echo
bravo
lima
zulu
alpha

Anyone has a clue how to do it so the result displayed on screen is just the one/ones matching the certain string, so, in other words, only items from array 1 that match the string in array 2? Many thanks for any hints, Tomas

Answer 1

If I understood your most recent explanation of the problem, what you really want to do is to match the GUID portion of the array elements (which is pretty much the same as my last answer, but using a different part of the elements):

$arr1 = "Sample st. 13-13, A City, 123456 State - Something and something else_ba6e1a5d-a8ef-480a-924f-cf61fea2813b",
        "Sample st. 13-13, A City, 123456 State - Something and something else_02483af8-21f4-4f97-be65-0b159b825318"

$arr2 = "Sample st. 13_13, A City, 123456 State - Something and something else_02483af8-21f4-4f97-be65-0b159b825318",
        "Sample st. 13_13, A City, 123456 State - Something and something else_6f4624ce-ad27-462f-8dbb-d8930298bd30"

$hash2 = @{}
foreach ($a2 in $arr2){
    if ($a2 -match '(\w{8}-\w{4}-\w{4}-\w{4}-\w{12})'){
        $hash2[($matches[1])] = $a2
    }
}

# if $arr1 contains a match in $arr2 emit the value from $arr1
foreach ($a1 in $arr1){
    if ($a1 -match '(\w{8}-\w{4}-\w{4}-\w{4}-\w{12})'){
        if ( $hash2.ContainsKey( $matches[1] )){
                $a1
        }
    }
}

Answer 2

Something like this will work:

[array]$arr1 = 'charlie','echo','bravo','lima','zulu','alpha'
[array]$arr2 = 'eagle', 'horse', 'cat', 'goat', 'dog', 'charlie'

$arr2 |
    ForEach-Object{
        $arr1 -eq $_
    }

Answer 3

If the only differences are the presence of the characters "-" or "_", then this will find them:

[array]$arr1 = 'abc_charlie123','echo','bravo','lima','zulu','alpha','abc_charlie456','abc_charlie789' 
[array]$arr2 = 'abc-charlie456', 'eagle', 'horse', 'cat', 'goat', 'dog', 'abc-charlie123','abc-charlie789'

# if $arr1 contains a match in $arr2 emit the value from $arr1
foreach ($a1 in $arr1){
    foreach ($a2 in $arr2){
        if ( ($a1 -replace "[_-]","") -eq ($a2 -replace "[_-]","") ){
            $a1
        }
    }
}

NOTE: That presents the absolute worst case for execution speed!

This code requires more memory but loops only once over $arr1 and $arr2, and it should run much faster. If the two data sets are in files, then creating the two arrays isn't necessary, which makes this much more preferable:

[array]$arr1 = 'abc_charlie123','echo','bravo','lima','zulu','alpha','abc_charlie456','abc_charlie789' 
[array]$arr2 = 'abc-charlie456', 'eagle', 'horse', 'cat', 'goat', 'dog', 'abc-charlie123','abc-charlie789'

$hash2 = @{}
foreach ($a2 in $arr2){
    $hash2[($a2 -replace "[_-]","")] = $a2
}

# if $arr1 contains a match in $arr2 emit the value from $arr1
foreach ($a1 in $arr1){
    $x = $a1 -replace "[_-]",""
    if ( $hash2.ContainsKey( $x )){
            $hash2.$x
    }
}