I'm trying to take an array of PSObjects similar to
#{BakId=27; Name=DB_A; Lsn=123; File=A_01; Size=987}
#{BakId=28; Name=DB_B; Lsn=456; File=B_01; Size=876}
#{BakId=28; Name=DB_B; Lsn=456; File=B_02; Size=765}
#{BakId=28; Name=DB_B; Lsn=456; File=B_03; Size=654}
And create a new grouped object that removes redundant header info.
BakId Lsn Name Files
27 123 DB_A {#{File=A_01.bak;Size=777}}
28 456 DB_B {#{File=B_01.bak;Size=888}, #{File=B_02.bak;Size=999}, ...}
I tried using group-object but can only get it to work for one property. (all grouped properties go into Group.Name as a a string of comma separated values.)
This is the best I've come up with, but feels hacky.
$list | Group-Object -Property BakId | % {
$BakId = $_.Name
$Lsn = $_.Group[0].Lsn # <--- is there a better way than this?
$Name = $_.Group[0].Name # <--- Ditto
$Files = $_.Group | Select-Object -Property SequenceNumber, Size
Write-Output (New-Object -TypeName PSObject -Property #{ BakId=$BakId;Files = $Files })
}
Is there a better way?
Thanks
You can simplify the approach to constructing the output objects by using a single Select-Object call with calculated properties, and, relying on the order of the grouping properties, access their group-specific values via the .Values collection:
$list | Group-Object -Property BakId, Lsn, Name |
Select-Object #{n='BakId'; e={ $_.Values[0] }},
#{n='Lsn'; e={ $_.Values[1] }},
#{n='Name'; e={ $_.Values[2] }},
#{n='Files'; e={ $_.Group | Select-Object File, Size }}
Note:
$_.Values[<ndx>] takes the place of $_.Group[0].<name> in your approach; note that the latter only makes sense for the actual grouping properties, because any others will not be uniform throughout the group.
The .Values collection ([System.Collections.ArrayList]) on each group object output from Group-Object ([Microsoft.PowerShell.Commands.GroupInfo] instance) contains that group's shared grouping-property values as-is (original type), in the order specified.
By contrast, property .Name contains the stringified combination of all grouping-property values: a string containing a comma-separated list.
Unfortunately, such details are currently missing from Get-Help Group-Object.
If you wanted to avoid having to repeat the grouping properties (e.g., in preparation for writing a function wrapper; PSv3+):
$props = 'BakId', 'Lsn', 'Name'
$list | Group-Object -Property $props | ForEach-Object {
$propDefs = [ordered] #{}
foreach ($i in 0..($props.Length-1)) { $propDefs.[$props[$i]] = $_.Values[$i] }
$propDefs.Files = $_.Group | Select-Object File, Size
New-Object PSCustomObject -Property $propDefs
}
Related
I keep running into the same problem again, and i have my default way of handling it, but it keeps bugging me.
Isn't there any better way?
So basicly i have a pipline running, do stuff within the pipline, and want to return a Key/Value Pair from within the pipline.
I want the whole pipline to return a object of type psobject (or pscustomobject).
Here is the way i do it everytime.
I create a hashtable at the beginning of the pipline and add key/Value Pairs from within the pipline to this hashtable using the .Add() method.
Afterwards i create a psobject by passing the hashtbale to New-Object`s -Property Parameter. This gives me the desired result.
Get-Process | Sort -Unique Name | ForEach-Object -Begin { $ht = #{} } -Process {
# DO STUFF
$key = $_.Name
$val = $_.Id
# Add Entry to Hashtable
$ht.Add($key,$val)
}
# Create PSObject from Hashtable
$myAwesomeNewObject = New-Object psobject -Property $ht
# Done - returns System.Management.Automation.PSCustomObject
$myAwesomeNewObject.GetType().FullName
But this seems a bit cluncky, isn't there a more elegant way of doing it?
Something like this:
[PSObject]$myAwesomeNewObject = Get-Process | Sort -Unique Name | ForEach-Object -Process {
# DO STUFF
$key = $_.Name
$val = $_.Id
# return Key/Val Pair
#{$key=$val}
}
# Failed - returns System.Object[]
$myAwesomeNewObject.GetType().FullName
This unfortunally dosn't work, since the pipe returns an array of hashtables, but i hope you know now what iam trying to achieve.
Thanks
Not sure if this is more elegant but just another way of doing it, this uses an anonymous function so $ht will no longer be available after execution, and casts to [pscustomobject] instead of using New-Object:
[pscustomobject] (Get-Process | Sort -Unique Name | & {
begin { $ht = #{ } }
process {
# DO STUFF
$key = $_.Name
$val = $_.Id
# Add Entry to Hashtable
$ht.Add($key, $val)
}
end { $ht }
})
You can also use the -End parameter to convert the final hash table to a pscustomobject as part of the pipeline, without needing to set the whole thing to a variable
$ht[$key]=$val is also a nice shorthand for $ht.Add($key,$val):
Get-Process |
Sort -Unique Name |
Foreach -Begin { $ht = #{} } -Process {
$ht[$_.Name] = $_.Id
} -End {[pscustomobject]$ht} |
## continue pipeline with pscustomobject
Thanks to #Santiago Squarzon and #Cpt.Whale answers, i were able to combine them to create a solution that pleases me:
$myAwesomeNewObject = `
Get-Process | Sort -Unique Name | & {
begin { $ht = #{} }
process {
# DO STUFF
$key = $_.Name
$val = $_.Id
# Add Entry to Hashtable
$ht[$key]=$val
}
end {[pscustomobject]$ht}
}
# Success - System.Management.Automation.PSCustomObject
$myAwesomeNewObject.Gettype().FullName
# And helper Hashtable is NULL thanks to the
# anonym function
$null -eq $ht
Thanks alot Guys
Alternatively you may create a hashtable using Group-Object -AsHashTable:
# Store the PIDs of all processes into a PSCustomObject, keyed by the process name
$processes = [PSCustomObject] (Get-Process -PV proc |
Select-Object -Expand Id |
Group-Object { $proc.Name } -AsHashtable)
# List all PIDs of given process
$processes.chrome
Notes:
Common parameter -PV (alias of -PipelineVariable) makes sure that we can still access the full process object from within the calculated property of the Group-Object command, despite that we have a Select-Object command in between.
The values of the properties are arrays, which store the process IDs of all instances of each process. E. g. $processes.chrome outputs a list of PIDs of all instances of the chrome process.
The code I am using is below:
Import-Csv -Path "E:\CSV\GA.csv" | Group-Object Product | ForEach {
New-Object PSObject -Property #{
Product = $_.Name
Stockcode = $_.Group[0].Stockcode
QuantityCounted = ($_.Group | Measure-Object -Property QuantityCounted -Sum).Sum
}
} | Export-Csv "E:\CSV\test.csv" -NoTypeInformation
The Headers should be in this order:
Product | Stockcode | QuantityCounted
If someone could point me in the right direction that would awesome, thank you.
Hash Tables are not ordered by default, if you need your object's properties to preserve their order you need to use an Ordered Dictionary instead.
The [ordered] attribute is introduced in PowerShell 3.0.
New-Object PSObject -Property ([ordered]#{
Product = 1
Stockcode = 2
QuantityCounted = 3
})
If you're running an up-to-date version of PowerShell, you can create objects with ordered properties using the [pscustomobject] type accelerator. This is more efficient and straight forward than New-Object.
The [pscustomobject] type accelerator was added in PowerShell 4.0.
[pscustomobject]#{
Product = 1
Stockcode = 2
QuantityCounted = 3
}
I would like the Application and ShortcutName columns to be grouped into one column, while keeping the Version and Architecture columns as they are :
$object | Select-Object -Property Application, Version, Architecture, ShortcutName |
Sort-Object -Property #{expression="Architecture";Descending=$true},Application |
Out-GridView
How can I do that ?
In PowerShell you group objects by properties with Group-Object. What you want is not grouping in that sense, but defining a new custom property.
You create custom properties a hashtable with the Name and Expression keys.
Something like this will probably do the trick.
$Expression = {
if ($_.Application) {
$_.Application
}
else {
$_.Shortcut
}
}
$object |
Select-Object -Property #{ Name = 'Application'; Expression = $Expression }, Version, Architecture |
Sort-Object -Property #{expression="Architecture";Descending=$true},Application |
Out-GridView
The expression checks whether the Application property is filled. If so, it will use the existing application name, otherwise it will take the Shortcut property as application name.
I am trying to find an elegant way to put the metadata of a table of type System.Data.DataTable into a multi-dimensional array for easy reference in my program. My approach to the issue so far seems tedious.
Assuming $DataTable being the DataTable in question
What I tried to do so far was:
$Types = $DataTable.Columns | Select-Object -Property DataType
$Columns= $DataTable.Columns | Select-Object -Property ColumnName
$Index = $DataTable.Columns | Select-Object -Property ordinal
$AllowNull = $DataTable.Columns | Select-Object -Property AllowDbNull
Then painfully going through each array, pick up individual items and put them in my multi-dimensional array $TableMetaData.
I read in the documentation of Select-Object and it seems to me that only 1 property can be selected at 1 time? I think I should be able to do all the above more elegantly and store the information in $TableMetaData.
Is there a way to easily pick up multiple properties and put them in a multi-dimensional array in 1 swoop?
I read the documentation of Select-Object and it seems to me that only 1 property can be selected at 1 time?
This is not true, Select-Object can take any number of arguments to the -Property parameter
$ColumnInfo = $DataTable.Columns | Select-Object -Property DataType,ColumnName,ordinal,AllowDbNull
Now $ColumnInfo will contain one object for each column, having all 4 properties.
Rather than using a multi-dimensional array, you should consider using a hashtable (#{}, an unordered dictionary):
$ColumnInfo = $DataTable.Columns | ForEach-Object -Begin { $ht = #{} } -Process {
$ht[$_.ColumnName] = $_
} -End { return $ht }
Here, we create an empty hashtable $ht (the -Begin block runs just once), then store each column object in $ht using the ColumnName as the key, and finally return $ht, storing it in $ColumnInfo.
Now you can reference metadata about each column by Name:
$ColumnInfo.Column2
# or
$ColumnInfo["Column2"]
One easy way to do this is to create an "empty" variable with Select-Object. Here is a sample command:
$DataTableReport = "" | Select-Object -Property DataType, ColumnName, ordinal, AllowDbNull
Then, link the $DataTableReport to the $Types, $Columns, $Index, and the $AllowNull properties as shown below:
$DataTableReport.Types = $DataTable.DataType
$DataTableReport.Columns = $DataTable.ColumnName
$DataTableReport.Index = $DataTable.ordinal
$DataTableReport.AllowNull = $DataTable.AllowDbNull
Finally, call the DataTableReport variable.
$DataTableReport # will display all the results in a tabular form.
I want to return an object from an array who's property has the highest value. Currently I am doing the following
Get-VM | Sort-Object -Property ProvisionedSpaceGB | Select-Object -Last 1
This works but is inefficient. I don't need the entire array sorted, I just need the object with largest value. Ideally I would use something like
Get-VM | Measure-Object -Property ProvisionedSpaceGB -Maximum
but this only returns the value of the object property, not the entire object. Is there a way to have measure-object return the base object?
Not directly. Measure-Object is intended to be an easy way to grab such values, not their input objects. You could get the maximum from Measure-Object and then compare against the array, but it takes a few steps:
$array = Get-VM
$max = ($array | measure-object -Property ProvisionedSpaceGB -maximum).maximum
$array | ? { $_.ProvisionedSpaceGB -eq $max}
You could also forgo Measure-Object entirely and iterate through the set, replacing the maximum and output as you go.
$max = 0
$array | Foreach-Object
{
if($max -le $_.ProvisionedSpaceGB)
{
$output = $_
$max = $_.ProvisionedSpaceGB
}
}
$output
This is a little dirtier so as to always return a single value. It would need a minor adjustment if you were to reuse it in a case where there may be multiple values that have the same maximum (filesize lengths when using Get-ChildItem, for example). It will replace $output with the latter iterate in a case where two or more objects have the same value for ProvisionedSpaceGB. You could turn $output into a collection easily enough to fix that.
I prefer the former solution myself, but I wanted to offer a different way to think about the problem.
You can use this:
$array = Get-VM | Sort-Object -Property ProvisionedSpaceGB -Descending
$array[0]