Loop through csv compare content with an array and then add content to csv - powershell

Question

I don't know how to append a string to CSV. What am I doing:
I have two csv files. One with a list of host-names and id's and another one with a list of host-names and some numbers.
Example file 1:
Hostname | ID
IWBW140004 | 3673234
IWBW130023 | 2335934
IWBW120065 | 1350213
Example file 2:
ServiceCode | Hostname | ID
4 | IWBW120065 |
4 | IWBW140004 |
4 | IWBW130023 |
Now I read the content of file 1 in a two dimensional array:
$pcMatrix = #(,#())
Import-Csv $outputFile |ForEach-Object {
foreach($property in $_.PSObject.Properties){
$pcMatrix += ,($property.Value.Split(";")[1],$property.Value.Split(";")[2])
}
}
Then I read the content of file 2 and compare it with my array:
Import-Csv $Group".csv" | ForEach-Object {
foreach($property in $_.PSObject.Properties){
for($i = 0; $i -lt $pcMatrix.Length; $i++){
if($pcMatrix[$i][0] -eq $property.Value.Split('"')[1]){
#Add-Content here
}
}
}
}
What do I need to do, to append $pcMatrix[$i][1] to the active column in file 2 in the row ID?
Thanks for your suggestions.
Yanick

Answer 1

It seems like you are over-complicating this task.
If I understand you correctly, you want to populate the ID column in file two, with the ID that corresponds to the correct hostname from file 1. The easiest way to do that, is to fill all the values from the first file into a HashTable and use that to lookup the ID for each row in the second file:
# Read the first file and populate the HashTable:
$File1 = Import-Csv .\file1.txt -Delimiter "|"
$LookupTable = #{}
$File1 |ForEach-Object {
$LookupTable[$_.Hostname] = $_.ID
}
# Now read the second file and update the ID values:
$File2 = Import-Csv .\file2.txt -Delimiter "|"
$File2 |ForEach-Object {
$_.ID = $LookupTable[$_.Hostname]
}
# Then write the updated rows back to a new CSV file:
$File2 | Export-CSV -Path .\file3.txt -NoTypeInformation -Delimiter "|"