Associative Array - how to return mapped values?

Hello PowerShellers,

How do I return a mapped value from an associative array?

I have this books.csv file:

ID,Author,Title
1,"Dr Seuss",Sneetches
2,Collins,"Good to Great"
3,Bolles,"What Color is Your Parachute"

Using PowerShell Import-csv cmdlet, I need to return the Title "Good to 
Great" for ID=2. Here is my attempt:

PS C:\> $books = Import-CSV books.csv  # populates the associate array
PS C:\> $books                                      # everything looks good
PS C:\> Write-Host $books.2                   # gives an error
PS C:\> Write-Host $books[2]                 # returns the 3rd record on 
Bolles
PS C:\> Write-Host $books[2].Author       # returns Bolles, not Collins

So, how do I query the associative array for ID=2 and return either the 
Author or Title property?

Thanks for the help,

The Microsoft TechNet article - What Can I Do With Windows PowerShell? Using 
the Import-Csv cmdlet 
(http://www.microsoft.com/technet/scriptcenter/topics/msh/cmdlets/import-csv.msp
x) shows how to select a record using the Where-Object

PS C:\> $books | Where-Object {$_.Author -eq "Collins"}    #
returns record

but I still have the problem on how to just return the a single value or 
column in the .csv file.

Also, I had no luck find the answer in the help file:
Get-Help about_Associative_Array

Thanks,

Jeff Jensen

"Jeffery Jensen" wrote:

> Hello PowerShellers,
> 
> How do I return a mapped value from an associative array?
> 
> I have this books.csv file:
> 
> ID,Author,Title
> 1,"Dr Seuss",Sneetches
> 2,Collins,"Good to Great"
> 3,Bolles,"What Color is Your Parachute"
> 
> Using PowerShell Import-csv cmdlet, I need to return the Title "Good
to 
> Great" for ID=2. Here is my attempt:
> 
> PS C:\> $books = Import-CSV books.csv  # populates the associate array
> PS C:\> $books                                      # everything looks
good
> PS C:\> Write-Host $books.2                   # gives an error
> PS C:\> Write-Host $books[2]                 # returns the 3rd record on

> Bolles
> PS C:\> Write-Host $books[2].Author       # returns Bolles, not Collins
> 
> So, how do I query the associative array for ID=2 and return either the 
> Author or Title property?
> 
> Thanks for the help,
> 

In PowerShell arrays are zero based. 

# filter the objects on a property that has a known value:
$books | where-object {$_.title -match 'Good to Great'}

# if you know the element's index and property
$books[1].title

# to view the elements members
$books | get-member

# to view the collection members
get-member -input $books

# or...
,$books | get-member


-- 
Kiron

Forgot to mention Where-Object's and Get-Member's aliases, '?' and 'gm'
respectively...

-- 
Kiron

Select-Object lets you choose which properties --or columns-- you want to
output, it also lets you create calculated properties. This Cmdlet returns
psObjects, they will have a header and their corresponding values. If you want
only values use ForEach-Object and get the properties from the current pipeline
object '$_'.

# for more on these Cmdlets
help select-object
help foreach-object

# selecting the Author column (header and value)
$books | select-object Author

# selecting just the values of the Author column
$books | foreach-object {$_.Author}

# filtering on Author and selecting the Title column (header and value)
$books | where-object {$_.Author -eq "Collins"} | select Title

# filtering and selecting the Title column's value, note the aliases
$books | ? {$_.Author -eq "Collins"} | % {$_.Title}

-- 
Kiron