Array subtraction in PowerShell - linq

I have an array of objects:
$people= #()
foreach ($person in $databaseOfGuests)
{
$people += #{ "FirstName"=$person.FirstName; "LastName"=$person.LastName }
}
Now I want to remove duplicates from $people, is it possible to do this in PowerShell? Something like:
$people = $people | Select -Uniq
I have two arrays $people1 and $people2, I need to get array of all people that are in $people1 but not in the $people2 and vise versa. Something like:
$peopleInPeople1ButNotInPeople2 = $people1.Substruct($people2)
$peopleInPeople2ButNotInPeople1 = $people2.Substruct($people1)
Is it possible to do it in one line in PS?

Try this:
$people1 | ? {$_ -notin $people2}
or you can filter by property, like firstname or lastname:
$people1 | ? {$_.Firstname -notin $people2.Firstname}
the -notin operator is available on PS3 and above, for lower versions you can use -notcontains

My first thought was to fall back to the .NET Framework and use LINQ. But it turns out that the PowerShell syntax is pretty ugly:
[Linq.Enumerable]::Except([object[]] $people1, [object[]] $people2)
(I'm not sure why the object[] casts are necessary, but without them PowerShell throws an "Cannot find an overload for "Except" and the argument count: "2"" exception.)

The idiomatic PowerShell would be:
$people1 | Where-Object { $people2 -notcontains $_ }

In addition to other good answers, following code depicts all SET operation on PowerShell Arrays:
#Union - Subtraction - Minus:
$a = (1,2,3,4)
$b = (1,2,77,88)
'UNION:'
Compare-Object $a $b -PassThru -IncludeEqual # union
''
'INTERSECTION:'
Compare-Object $a $b -PassThru -IncludeEqual -ExcludeDifferent # intersection
''
'MINUS:'
'$a minus $b:'
$a | ?{$b -notcontains $_} # a -minus b
'$b minus $a:'
$b | ?{$a -notcontains $_} # b -minus a
HTH.

Related

using -replace to remove a string with special characters from cells in a csv

I have a CSV file like:
"localpath"
"C:\Users\calabresel"
"C:\Users\goslinep"
"C:\Users\deangelisr"
"C:\Users\bannont"
"C:\Users\goodwind"
I am looking for a way to isolate just the username from each field. I will then query the AD to determine if each user is disabled or enabled. I haven't been able to figure out how to get just the last piece though. My idea was to use -replace to replace the identical string with null like this:
$txt = import-csv paths1.csv | % {$_.localpath = $_.localpath -replace "C:\Users\", ""}
That came back with invalid regular expression pattern errors though which I assumed was a result of the target string containing special characters (the backslashes). I then started looking for a way to get powershell to take the \ literally instead. That lead me to try this:
$txt = import-csv paths1.csv | % {$_.localpath = $_.localpath -replace [Regex]::Escape("C:\\Users\\"), ""}
and this
$txt = import-csv paths1.csv | % {$_.localpath = $_.localpath -replace "C:\\Users\\", ""}
both of those methods stop the invalid regular expression errors and just return me a fresh line without complaining. however when I print the $txt variable it is empty...
I'm certain I am approaching this problem from the wrong angle and/or with improper syntax but I could use some guidance as I just started working with powershell a week ago.
any help provided would be greatly appreciated.
The following will import the CSV file and then get the leaf of the path. I.e the user name.
$txt = Import-Csv paths1.csv | ForEach-Object { Split-Path $_.localpath -leaf }
If you still want to use your replace method, just take out the $_.localpath = part and it should work.
$txt = Import-Csv C:\##Scatch\test.csv | % { $_.localpath -replace "C:\\Users\\", ""}
The reason why you aren't getting anything back into $txt is that you update a property of $_ but don't return $_.
Assuming that you want to use the regex rather than Split-Path
$txt = import-csv C:\temp\test.csv | % {
$_.localpath = $_.localpath -replace "C:\\Users\\", ""
$_
}
Or
$txt = import-csv C:\temp\test.csv | % {
$_.localpath -replace "C:\\Users\\", ""
}
other solution
Get-Content "C:\temp\test.txt" | select #{N="Value";E={$_.split('\')[-1].replace('"', '')}} -Skip 1

Find username in array beginning with 'n'

I have a hash table from AD containing usernames and service accounts. I'm trying to find all the service accounts. All usernames are uniquely identified by their first letters such as 'r' and service accounts with 's'. For example: r398831 and s882443. Here's an example of the array I have:
$null = $usrArr.Add([pscustomobject] #{
sName = $user.name
sGivenName = $user.GivenName
sSurname = $user.Surname
sEnabled = $user.Enabled
})
$lastSeen = $usrArr | select * | Where {$_.sEnabled -eq $true}
$lastSeen = $lastSeen | Sort-Object -Unique -Property sName
I've tried using -contains and -match but it doesn't seem to pull back what I'm after:
$svcAcc = $lastSeen | where-object {$_.sName -like "s"}
Do I have to perform a for each or have I just messed up my Syntax on this?
I'm thinking maybe I need to sort-object but there has to be a more simple way to pull off something so basic. Appreciate any advice on it.
Thanks in advance :)
Best,
Pete
The -like operator matches the wildcard pattern on the RHS against the entire LHS, so -like "s" would only ever match values that are in full identical to literal s.
To instead match inputs that start with literal s, use wildcard pattern s*:
$svcAcc = $lastSeen | where-object { $_.sName -like 's*' }
As an aside: Your use of select * seems redundant; similarly, -eq $true is not strictly necessary, so assigning to $lastSeen can be simplified to:
$lastSeen = $usrArr | Where-Object sEnabled | Sort-Object -Unique -Property sName
Note that Where-Object sEnabled is short for Where-Object { $_.sEnabled }, which is a syntax simplification introduced in PSv3, called a comparison statement.
You can use -match like you were trying to do but just turn your query into a regular expression using the caret anchor character.
$usrArr | Where-Object { $_.sName -match "^s" }

powershell - possible to sort by string extracted from alllelements using custom property?

I thought this would be a pretty simple undertaking - a program that returns webrequest elements and sorts them by a custom property which, in this case, is a substring "extracted" from $_.innertext. (Specifically, I want to sort a list of "deals" which are described in various ways by $-amount.)
But even simple string operations on $_.innertext don't seem to work, always yielding an error of this sort.
Sort-Object : You cannot call a method on a null-valued expression.
Here is the code I am working with - I'll appreciate any guidance, whether pointing out code issues or suggesting alternative methods.
# function to scrub text from a Class filtering on keyword, sort by $*
function Get-Deals {
param($keyword)
$url = "https://slickdeals.net/newsearch.php?q=$keyword"
$result = Invoke-WebRequest $url
$result.AllElements |
Where Class -eq "dealTitle" |
Where {($_.innertext -match ($keyword)) -and ($_.innertext -match ("$"))} |
Sort-Object #{Expression={$_.inntertext.substring($_.innertext.IndexOf('$'))}} |
Select -ExpandProperty innerText
}
Get-Deals("TV")
Here's a (partial) solution to the problem I initially asked about. Code below - note these 2 changes:
$_.innertext enclosed in quotation marks in sort statement
some changes to Where criteria to make sure I was filtering adequately to ensure all elements have a '$' in them (previously I was missing some cases).
Here's why I said this is only a "(partial)" solution: Right now my sort is working, but I'm sorting based on strings, not by numbers. So $9.99 will come after $1999.99.
But that's an entirely different problem from what I initially asked about.
function Get-Deals {
param($keyword)
$url = "https://slickdeals.net/newsearch.php?q=$keyword"
$result = Invoke-WebRequest $url
$result.AllElements |
Where Class -eq "dealTitle" |
Where {( ($_.innertext -match ($keyword)) -and ($_.innertext -like '*$*') )} |
#Where {$_.innertext -like '*$*'} |
Sort-Object #{Expression={"$_.innertext".substring("$_.innertext".IndexOf('$'))}} |
Select -ExpandProperty innerText
}
Get-Deals("TV")

powershellv2 - how to sort a list after splitting the string

I have a file containing a list of email addresses:
e.g.
personB#placeB.com
nameA#location2.com
nameB#location2.com
I want to order them, but by the domain, and then by the local, and then output the ordered list. so I end up with:
nameA#location2.com
nameB#location2.com
personB#placeB.com
I can use sort-object to order them, but this is by the whole string.
So far I have got this far:
SELECT-STRING -path path_To_My_File |
FOREACH{
$a = $_.split"(#)"
$local = $a[0]
$domain = $a[1]
}
but can't see how to incorporate the sort-object.
Similar to Matt's answer, but will give you the sorted email addresses as a list:
$addresses = #()
Get-Content .\path\to\file | % {
$n = $($_ -split '#')[0]
$d = $($_ -split '#')[1]
$o = New-Object PSObject -property #{name=$n;domain=$d;email=$_}
$addresses += ,$o
}
$addresses | sort domain,name | select -ExpandProperty email
The $addresses array can be sorted by the object you created on the fly in the Foreach-Object or % loop, and then you can just select the email property to give you the sorted list
Sort-Object obviously needs an object to sort on. So we can create an object like this. ( There are other ways as well). Also we dont need to use select-string since you are applying no patterns
Get-Content -path "path_To_My_File" |
Select-Object #{Name="Local";Expression={($_.split("#"))[0]}},#{Name="Domain";Expression={($_.split("#"))[1]}} |
Sort-Object domain,local
Create properties using Select-Object for Local and Domain using the same split that you had. The select on its own would output this:
Local Domain
----- ------
personB placeB.com
nameA location2.com
nameB location2.com
Then we can sort to get this:
Local Domain
----- ------
nameA location2.com
nameB location2.com
personB placeB.com
If you need the full address as well we can shorten the code and add that variable.
Get-Content -path "path_To_My_File" |
Select #{N="Address";E={$_}},
#{N="Local";E={($_.split("#"))[0]}},
#{N="Domain";E={($_.split("#"))[1]}} |
Sort domain,local

PowerShell equivalent of LINQ Any()?

I would like to find all directories at the top level from the location of the script that are stored in subversion.
In C# it would be something like this
Directory.GetDirectories(".")
.Where(d=>Directories.GetDirectories(d)
.Any(x => x == "_svn" || ".svn"));
I'm having a bit of difficulty finding the equivalent of "Any()" in PowerShell, and I don't want to go through the awkwardness of calling the extension method.
So far I've got this:
Get-ChildItem | ? {$_.PsIsContainer} | Get-ChildItem -force | ? {$_.PsIsContainer -and $_.Name -eq "_svn" -or $_.Name -eq ".svn"
This finds me the svn directories themselves, but not their parent directories - which is what I want. Bonus points if you can tell me why adding
| Select-Object {$_.Directory}
to the end of that command list simply displays a sequence of blank lines.
To answer the immediate question with a PowerShell v3+ solution:
(Get-ChildItem -Force -Directory -Recurse -Depth 2 -Include '_svn', '.svn').Parent.FullName
-Directory limits the matches to directories, -Recurse -Depth 2 recurses up to three levels (children, grandchildren, and great-grandchildren), Include allows specifying multiple (filename-component) filters, and .Parent.FullName returns the full path of the parent dirs. of the matching dirs., using member-access enumeration (implicitly accessing a collection's elements' properties).
As for the bonus question: select-object {$_.Directory} does not work,
because the \[System.IO.DirectoryInfo\] instances returned by Get-ChildItem have no .Directory property, only a .Parent property; Select-Object -ExpandProperty Parent should have been used.
In addition to only returning the property value of interest, -ExpandProperty also enforces the existence of the property. By contrast, Select-Object {$_.Directory} returns a custom object with a property literally named $_.Directory, whose value is $null, given that the input objects have no .Directory property; these $null values print as empty lines in the console.
As for the more general question about a PowerShell equivalent to LINQ's .Any() method, which indicates [with a Boolean result] whether a given enumerable (collection) has any elements at all / any elements satisfying a given condition:
Natively, PowerShell offers no such equivalent, but the behavior can be emulated:
Using the PowerShell v4+ intrinsic.Where() method:
Caveat: This requires collecting the entire input collection in memory first, which can be problematic with large collections and/or long-running input commands.
(...).Where({ $_ ... }, 'First').Count -gt 0
... represents the command of interest, and $_ ... the condition of interest, applied to each input object, where PowerShell's automatic $_ variable refers to the input object at hand; argument 'First' ensures that the method returns once the first match has been found.
For example:
# See if there's at least one value > 1
PS> (1, 2, 3).Where({ $_ -gt 1 }, 'First').Count -gt 0
True
Using the pipeline: Testing whether a command produced at least one output object [matching a condition]:
The advantage of a pipeline-based solution is that it can act on a command's output one by one, as it is being produced, without needing to collect the entire output in memory first.
If you don't mind that all objects are enumerated - even if you only care if there is at least one - use Paolo Tedesco's helpful extension to JaredPar's helpful answer.
The down-side of this approach is that you always have to wait for a (potentially long-running) command to finish producing all output objects, even though - logically - the determination whether there are any output objects can be made as soon as the first object is received.
If you want to exit the pipeline as soon as one [matching] object has been encountered, you have two options:
[Ad-hoc: Easy to understand, but cumbersome to implement]
Enclose the pipeline in a dummy loop and use break to break out of the pipeline and that loop (... represents the command whose output to test, and $_ ... match the condition):
# Exit on first input object.
[bool] $haveAny = do { ... | % { $true; break } } while ($false)
# Exit on first input object that matches a condition.
[bool] $haveAny = do { ... | % { if ($_ ...) { $true ; break } } } while ($false)
[Use a PowerShell v3+ self-contained utility function that is nontrivial to implement]
See the implementation of function Test-Any below.
It can be added to scripts or, for use in interactive sessions, to your $PROFILE file.
PowerShell v3+: Optimized utility function Test-Any
The function is nontrivial, because as of PowerShell (Core) v7.2.x, there is no direct way to exit a pipeline prematurely, so a workaround based on .NET reflection and a private type is currently necessary.
If you agree that there should be such a feature, take part in the conversation in GitHub issue #3821.
#requires -version 3
Function Test-Any {
[CmdletBinding()]
param(
[ScriptBlock] $Filter,
[Parameter(ValueFromPipeline = $true)] $InputObject
)
process {
if (-not $Filter -or (Foreach-Object $Filter -InputObject $InputObject)) {
$true # Signal that at least 1 [matching] object was found
# Now that we have our result, stop the upstream commands in the
# pipeline so that they don't create more, no-longer-needed input.
(Add-Type -Passthru -TypeDefinition '
using System.Management.Automation;
namespace net.same2u.PowerShell {
public static class CustomPipelineStopper {
public static void Stop(Cmdlet cmdlet) {
throw (System.Exception) System.Activator.CreateInstance(typeof(Cmdlet).Assembly.GetType("System.Management.Automation.StopUpstreamCommandsException"), cmdlet);
}
}
}')::Stop($PSCmdlet)
}
}
end { $false }
}
if (-not $Filter -or (Foreach-Object $Filter -InputObject $InputObject)) defaults to true if $Filter wasn't specified, and otherwise evaluates the filter (script block) with the object at hand.
The use of ForEach-Object to evaluate the filter script block ensures that $_ binds to the current pipeline object in all scenarios, as demonstrated in PetSerAl's helpful answer here.
The (Add-Type ... statement uses an ad-hoc type created with C# code that uses reflection to throw the same exception that Select-Object -First (PowerShell v3+) uses internally to stop the pipeline, namely [System.Management.Automation.StopUpstreamCommandsException], which as of PowerShell v5 is still a private type.
Background here:
http://powershell.com/cs/blogs/tobias/archive/2010/01/01/cancelling-a-pipeline.aspx
A big thank-you to PetSerAl for contributing this code in the comments.
Examples:
PS> #() | Test-Any false
PS> Get-EventLog Application | Test-Any # should return *right away* true
PS> 1, 2, 3 | Test-Any { $_ -gt 1 } # see if any object is > 1 true
Background information
JaredPar's helpful answer and Paolo Tedesco's helpful extension fall short in one respect: they don't exit the pipeline once a match has been found, which can be an important optimization.
Sadly, even as of PowerShell v5, there is no direct way to exit a pipeline prematurely.
If you agree that there should be such a feature, take part in the conversation in GitHub issue #3821.
A naïve optimization of JaredPar's answer actually shortens the code:
# IMPORTANT: ONLY EVER USE THIS INSIDE A PURPOSE-BUILT DUMMY LOOP (see below)
function Test-Any() { process { $true; break } end { $false } }
The process block is only entered if there's at least one element in the pipeline.
Small caveat: By design, if there's no pipeline at all, the process block is still entered, with $_ set to $null, so calling Test-Any outside of a pipeline unhelpfully returns $true. To distinguish between between $null | Test-Any and Test-Any, check $MyInvocation.ExpectingInput, which is $true only in a pipeline: Thanks, PetSerAl
function Test-Any() { process { $MyInvocation.ExpectingInput; break } end { $false } }
$true, written to the output stream, signals that at least one object was found.
break then terminates the pipeline and thus prevents superfluous processing of additional objects. HOWEVER, IT ALSO EXITS ANY ENCLOSING LOOP - break is NOT designed to exit a PIPELINEThanks, PetSerAl
.
If there were a command to exit the pipeline, this is where it would go.
Note that return would simply move on to the next input object.
Since the process block unconditionally executes break, the end block is only reached if the process block was never entered, which implies an empty pipeline, so $false is written to the output stream to signal that.
Unfortunately there is no equivalent in PowerShell. I wrote a blog post about this with a suggestion for a general purpose Test-Any function / filter.
function Test-Any() {
begin {
$any = $false
}
process {
$any = $true
}
end {
$any
}
}
Blog post: Is there anything in that pipeline?
A variation on #JaredPar's answer, to incorporate the test in the Test-Any filter:
function Test-Any {
[CmdletBinding()]
param($EvaluateCondition,
[Parameter(ValueFromPipeline = $true)] $ObjectToTest)
begin {
$any = $false
}
process {
if (-not $any -and (& $EvaluateCondition $ObjectToTest)) {
$any = $true
}
}
end {
$any
}
}
Now I can write "any" tests like
> 1..4 | Test-Any { $_ -gt 3 }
True
> 1..4 | Test-Any { $_ -gt 5 }
False
You can use the original LINQ Any:
[Linq.Enumerable]::Any($list)
It's actually quite simple - just select first $true (formatted for clarity):
[bool] ($source `
| foreach { [bool] (<predicate>) } `
| where { $_ } `
| select -first 1)
Alternative way:
($source `
| where { <predicate> } `
| foreach { $true } `
| select -first 1)
My approach now was:
gci -r -force `
| ? { $_.PSIsContainer -and $_.Name -match "^[._]svn$" } `
| select Parent -Unique
The reason why
select-object {$_.Directory}
doesn't return anything useful is that there is no such property on a DirectoryInfo object. At least not in my PowerShell.
To elaborate on your own answer: PowerShell can treat most non-empty collections as $true, so you can simply do:
$svnDirs = gci `
| ? {$_.PsIsContainer} `
| ? {
gci $_.Name -Force `
| ? {$_.PSIsContainer -and ($_.Name -eq "_svn" -or $_.Name -eq ".svn") }
}
I ended up doing it with a count:
$directoryContainsSvn = {
(Get-ChildItem $_.Name -force | ? {$_.PsIsContainer -and $_.Name -eq "_svn" -or $_.Name -eq ".svn"} | Measure-Object).Count -eq 1
}
$svnDirs = Get-ChildItem | ? {$_.PsIsContainer} | ? $directoryContainsSvn
You can tighten this up a bit:
gci -fo | ?{$_.PSIsContainer -and `
(gci $_ -r -fo | ?{$_.PSIsContainer -and $_ -match '[_.]svn$'})}
Note - passing $__.Name to the nested gci is unnecessary. Passing it $_ is sufficent.
I recommend the following solution:
<#
.SYNOPSIS
Tests if any object in an array matches the expression
.EXAMPLE
#( "red", "blue" ) | Where-Any { $_ -eq "blue" } | Write-Host
#>
function Where-Any
{
[CmdletBinding()]
param(
[Parameter(Mandatory = $True)]
$Condition,
[Parameter(Mandatory = $True, ValueFromPipeline = $True)]
$Item
)
begin {
[bool]$isMatch = $False
}
process {
if (& $Condition $Item) {
[bool]$isMatch = $true
}
}
end {
Write-Output $isMatch
}
}
# optional alias
New-Alias any Where-Any
This is the best method that I found so far (does not iterate over all elements if already found a true, and does not break the pipeline):
From LINQ Any() equivalent in PowerShell
It’s possible to use a built-in $input variable that contains the whole pipeline in a scope of function.
So, the desired code could look like the following:
function Test-Any([scriptBlock] $scriptBlock = {$true}, [scriptBlock] $debugOut = $null)
{
if ($debugOut)
{
Write-Host(“{0} | % {{{1}}}” -f $input, $scriptBlock)
}
$_ret = $false;
$_input = ($input -as [Collections.IEnumerator])
if ($_input)
{
while ($_input.MoveNext())
{
$_ = $_input.Current;
Write-Host $_
if ($debugOut)
{
Write-Host(“Tested: [{0}]” -f (&$debugOut))
}
if (&$scriptBlock)
{
if ($debugOut)
{
Write-Host(“Matched: [{0}]” -f (&$debugOut))
}
$_ret = $true
break
}
}
}
$_ret
}
I think that the best answer here is the function proposed by #JaredPar, but if you like one-liners as I do I'd like to propose following Any one-liner:
# Any item is greater than 5
$result = $arr | %{ $match = $false }{ $match = $match -or $_ -gt 5 }{ $match }
%{ $match = $false }{ $match = $match -or YOUR_CONDITION }{ $match } checks that at least one item match condition.
One note - usually the Any operation evaluates the array until it finds the first item matching the condition. But this code evaluates all items.
Just to mention, you can easily adjust it to become All one-liner:
# All items are greater than zero
$result = $arr | %{ $match = $false }{ $match = $match -and $_ -gt 0 }{ $match }
%{ $match = $false }{ $match = $match -and YOUR_CONDITION }{ $match } checks that all items match condition.
Notice, that to check Any you need -or and to check All you need -and.
I took a more linq-style approach.
I know this question is probably super old. I used this to accomplish my needs:
PS> $searchData = "unn"
PS> $StringData = #("unn", "dew", "tri", "peswar", "pymp")
PS> $delegate = [Func[string,bool]]{ param($d); return $d -eq $searchData }
PS> [Linq.Enumerable]::Any([string[]]$StringData, $delegate)
Taken from here:
https://www.red-gate.com/simple-talk/dotnet/net-framework/high-performance-powershell-linq/#post-71022-_Toc482783751

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