Vista Tutorial - Compare 2 files with 6,000 entries each

I've got one text file, and one csv file. As per a previous thread, I
wasn't able to figure out how to use compare-object to get all the
matches from each file (Keith pointed out that I'd need -synchWindow to
compare > 100 lines, but I haven't tried it yet).

The only way I've found to match up each file is to load each file:

$txt=get-content users.txt
$csv=import-csv users.csv

Then do something *ugly* like this:

$matches=$csv|%{$user=$_;$txt|%{if($_.contains($user)){$_}}}

So I loop through each entry in $csv, assign the current value to $user,
then loop through each entry in $txt looking for a match.

It is taking a *long* time...

Any performance improvement hints? If the above ever finishes, I'll
give compare-object a spin.

Marco

$csv = import-csv users.csv
# if users list is not of unique users already
# $csv | sort-object user -unique
get-content users.txt | foreach-object {if($csv -contains $_) {$_}}


--
Kiron

Excuse the typo...

# if users list is not of unique users already
# $csv = import-csv users.csv | sort-object <user_field> -unique


--
Kiron

"Marco Shaw" <marco.shaw@_NO_SPAM_gmail.com> wrote in message
news:eOmJPg$vHHA.1164@TK2MSFTNGP02.phx.gbl...
> I've got one text file, and one csv file. As per a previous thread, I
> wasn't able to figure out how to use compare-object to get all the matches
> from each file (Keith pointed out that I'd need -synchWindow to compare >
> 100 lines, but I haven't tried it yet).
>
> The only way I've found to match up each file is to load each file:
>
> $txt=get-content users.txt
> $csv=import-csv users.csv
>
> Then do something *ugly* like this:
>
> $matches=$csv|%{$user=$_;$txt|%{if($_.contains($user)){$_}}}

It will be difficult to avoid having 36,000,000 comparisons (6,000 lines
compared to 6,000 lines each). The simplest way I can express it in
PowerShell is this:

PS> gc file1.txt | ? {(gc file2.txt) -contains $_}

If the files have very different sizes, replace file1.txt with the biggest
file and replace file2.txt with the smallest one.
If file2.txt is still quite big, too big to be read from disk everytime, you
can save some cycles by assigning it to a variable first:

PS> $ref = gc file2.txt; gc file1.txt | ? {$ref -contains $_}

Hope that helps... Very late here, so I'd rather go sleep...

Jacques

Kiron wrote:
> $csv = import-csv users.csv
> # if users list is not of unique users already
> # $csv | sort-object user -unique
> get-content users.txt | foreach-object {if($csv -contains $_) {$_}}
>
>

Wow! The old method took 1 hour 39 minutes, this way took 26 seconds.
My only problem is that the old way returned 86 matches, but this faster
way returned only 35.

Something is up...

Is the matching list (users.csv) made up of unique user names?
The containment operators (-contains and -notcontains) will stop checking if
the right operand is present in the left operand and move on to compare the
next object in the pipeline.

0..7 | where-object { 1, 3, 5, 3 -contains $_ }
1
3
5

It only returns 3 once. The 'old way' was matching against each element, if
there were repeated users in $csv you would have more results. Hence the
unique users list question. Note the use of where-object, Jacques is right,
this way is more efficient than:

0..7 | foreach-object { if(1, 3, 5, 3 -contains $_) {$_} }

--
Kiron