Powershell Compare and Merge two arrays - arrays

Question

I'm very new to Powershell and what I want to do is to compare two arrays of data and then merge them together to one large array that I can either export to Excel or POST request to a web server using restful API and json.
To do this in Python is simple by using Pandas and adding search data but in Powershell I can't really get it done.
Example: I have 2 arrays
$a1 = #(('Name1', 'Link1', 'URL1'),
('Name2', 'Link2', 'URL2'),
('Name3', 'Link3', 'URL3')
)
$a2 = #(('Name4', 'URL4', 'TEXT4'),
('Name2', 'URL2', 'TEXT1'),
('Name1', 'URL1', 'TEXT2')
)
I want to do a compare $a1 with $a2 and the other way around so I don't miss any values.
Merge them together so I will end up with a $a3 array that look something like this.
$a3 = #(('Name1', 'Link1', 'URL1', 'TEXT1),
('Name2', 'Link2', 'URL2', 'TEXT2),
('Name3', 'Link3', 'URL3', ''),
('Name4', 'URL4', '', 'TEXT4')
)
And as more I dig in to different alternatives as more confused do I get.

Answer 1

I'd recommend to make a collection of (at least) simple objects to work with.
This is almost classic task of combining two different sets of properties by common key. Just convert those arrays-of-arrays to arrays-of-objects-with-properties and combine them next.
Please note that powershell is primary sysadmin's language, there is almost no place for any guesses or chances when processing tasks.
Also you can use almost any external .Net-DLL library in PowerShell (search Deedle as alternative to Pandas)
$a1 = #(('Name1', 'Link1', 'URL1'),
('Name2', 'Link2', 'URL2'),
('Name3', 'Link3', 'URL3')
)
$a2 = #(('Name4', 'URL4', 'TEXT4'),
('Name2', 'URL2', 'TEXT1'),
('Name1', 'URL1', 'TEXT2')
)
# Make Hashtable K=Name;V={Name, Link, Url, Text}
$AObjects = #{}
# Fill Hashtable from A1
#($a1) |
ForEach-Object {
$name = $_[0]
$AObjects[$name] = #{
Name = $name
Link = $_[1]
Url = $_[2]
Text = ''
}
}
# Fill Hashtable from A2
#($a2) |
ForEach-Object {
$name = $_[0]
$url = $_[1]
if (-not $AObjects.ContainsKey($name)) {
Write-Warning "A2 has [$name] that was not listed in A1!"
$AObjects[$name] = #{Name = $name; Url = $url; Link = ''; Text = ''}
} elseif($AObjects[$name].Url -ne $url) {
Write-Warning "For $($name), A1's URL and A2's URL differ! Using A1's"
}
$AObjects[$name].Text = $_[2]
}
# Convert Hashtable to array of objects with props. Select is required for better output.
$AObjects = #($AObjects.Values) | % { [PSCustomObject]$_ } | Select-Object #('Name', 'Link', 'URL', 'Text')
# Convert array of objects with props back to array
$result = $AObjects |
ForEach-Object {
if ([string]::IsNullOrWhiteSpace($_.Link)) { # Didn't get your logic swapping elements in example
return #(,#($_.Name, $_.Url, $_.Link, $_.Text))
} else {
return #(,#($_.Name, $_.Link, $_.Url, $_.Text))
}
}
#Print
$result | % { "[$($_ -join ',')]" }
# [Name3,Link3,URL3,]
# [Name1,Link1,URL1,TEXT2]
# [Name2,Link2,URL2,TEXT1]
# [Name4,URL4,,TEXT4]