unfortunately it was not working as i intended.
so i have new code with some help now:
using $column variable, i can control which column (from 1 to 4) i want to be
printed with column 5.
open(IN_FH,"<","infile") or die "Cannot open infile because: $!";
open(OUT_FH,">","outfile") or die "Cannot open outfile because: $!";
foreach $line (<IN_FH>){
@tmpAR=split(/ /,$line,5); #/ +/ will
split at any number of white spaces...
next if $tmpAR[$column] == 0;
push(@tmpAR2,"$tmpAR[$column] $tmpAR[4]"); # we can use -1 here as
last element of array
}
print OUT_FH sort { (split(/ /,$a))[0] <=> (split(/ /,$b))[0] } @tmpAR2;
close IN_FH;
close OUT_FH;
sample data in infile:
1 0 0 0 some text
0 2 0 3 text....
3 1 4 2 text....
4 3 1 1 text......
From: John W. Krahn <jwkr...@shaw.ca>
To: Perl Beginners <beginners@perl.org>
Sent: Friday, September 2, 2011 2:12 PM
Subject: Re: how to do this in perl (from unix)
Rajeev Prasad wrote:
> Thank you John,
>
> that is almost perfect. only two issues:
>
> 1. getting error on sort for each line of input, column 5 onwards is text...:
> Argument "154 Overload Status\n" isn't numeric in sort at ./test.pl line
>30,<IN_FH> line 208.
> 2. by chaniging the column number in join (...[0,-1]) to (...[2,-1]) I am
> not getting column 2 and 5 in output, it still send column 1 and 5 in output
> file.
>
> again, that was cool.
> -Rajeev
>
>
> from Linux:
> cut -f1,5- -d" " file |grep -v "^0" | sort -n> to_file
> to perl:
> open IN_FH, '<', 'file' or die "Cannot open 'file' because: $!";
> open OUT_FH, '>', 'to_file' or die "Cannot open 'to_file' because: $!";
> print OUT_FH sort { $a<=> $b } map /^0/ ? () : join( ' ', ( split / +/, $_,
> 5 )[ 0, -1 ] ),<IN_FH>;
>
> I tried to put my understanding in words:
> 1. 0. operations starts from right most part of statement (statement ends
> with ;)
> 2. split = breaks the line (contained in $_)
> / +/ = any number of white space
> $_ = the current line in in-built perl string variable
> 5 = number of fields string will be split into
> 3. join = joins the new resulting string from eariler split
> ' ' = uses single space as seperator
> [0,-1] = element 0 and -1 of array repersented by (split...)
> 4. map =<=========================================not able to understand
> map (map expr, list )
> /^0/ = expression to check wether line starts with 0
> ? = if line starts with zero then ??? not sure....
> () = not sure...
> : = not sure...
> 5. sort = sorts the final array on first column (which is by the way
> numerical)
> 6. OUT_FH = writes the outcome to the file_handle.
The flow goes from <IN_FH> to map to sort to print.
<IN_FH> reads the file lines and passes the list of lines to map.
map has each line in $_. This is matched with /^0/ and if it does match then
return the empty list and if it doesn't match remove columns 2, 3 and 4 and
then pass the resulting list to sort
sort does a numerical sort and then passes the sorted list to print.
print prints out the list to the filehandle OUT_FH.
To remove the error message you could do this:
{ no warnings;
print OUT_FH sort { $a <=> $b } map /^0/ ? () : join( ' ', ( split / +/,
$_, 5 )[ 0, -1 ] ), <IN_FH>;
}
John
-- Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
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