Simplify PowerShell code

Question

Trying to simplify this code for obvious reasons..... found this little snippit as a start, but I'm not really sure how to incorporate it into the larger scheme.

It's basically a phonebook CSV file that we need broken out into multiple files. The code below does work but it's very inefficient:

[char[]](65..90)

Code below:

GC C:\Users\x\documents\Telephonebook.csv | %{
if ($_.StartsWith("A")){
$_ | out-file -filepath c:\users\aricci\documents\A.asp -append
}

ElseIf ($_.StartsWith("B")){
$_ | out-file -filepath c:\users\aricci\documents\B.asp -append
}

ElseIf ($_.StartsWith("C")){
$_ | out-file -filepath c:\users\aricci\documents\C.asp -append
}

ElseIf ($_.StartsWith("D")){
$_ | out-file -filepath c:\users\aricci\documents\D.asp -append
}

ElseIf ($_.StartsWith("E")){
$_ | out-file -filepath c:\users\aricci\documents\E.asp -append
}

ElseIf ($_.StartsWith("F")){
$_ | out-file -filepath c:\users\aricci\documents\F.asp -append
}

ElseIf ($_.StartsWith("G")){
$_ | out-file -filepath c:\users\aricci\documents\G.asp -append
}

ElseIf ($_.StartsWith("H")){
$_ | out-file -filepath c:\users\aricci\documents\H.asp -append
}

ElseIf ($_.StartsWith("I")){
$_ | out-file -filepath c:\users\aricci\documents\I.asp -append
}

ElseIf ($_.StartsWith("J")){
$_ | out-file -filepath c:\users\aricci\documents\J.asp -append
}

ETC....

Mathias R. Jessen · Accepted Answer · 2016-10-10 19:15:38Z

6

Martin's answer would definitely work, but if you want to soften the IO overhead, you could use the Group-Object cmdlet to group the entries by first letter and then write all of them to each file once:

$Sets = Get-Content C:\Users\x\documents\Telephonebook.csv |Group-Object {$_[0]} 
foreach($Set in $Sets) {
    $Set.Group |Out-File ("c:\users\aricci\documents\{0}.asp" -f $Set.Name[0]) 
}

As Ansgar points out in the comments, this approach is more memory intensive than just using the pipeline

edited Oct 10, 2016 at 19:15

answered Oct 10, 2016 at 18:38

Mathias R. Jessen

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Ansgar Wiechers Over a year ago

Might be worth noting that this approach should be avoided for very large files, though (file doesn't fit in the available memory => system starts swapping => operation slows to a crawl).

Martin Brandl · Accepted Answer · 2016-10-10 18:33:56Z

2

The following will just use the first character as the filename (be aware that this could also be a number which you can exclude using a filter):

GC C:\Users\x\documents\Telephonebook.csv | % {
    $_ | out-file -filepath ("c:\users\aricci\documents\{0}.asp" -f $_[0]) -append    
}

answered Oct 10, 2016 at 18:33

Martin Brandl

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