PERL: line by line text parsing script - regex

for excercise and curiosity, anyone knows if the following script can be made more compact and expedite:
foreach(#list){
if ($_=~"givenName: ") {
$cname=$_;
$cname=~ s/givenName: //g;
}
if ($_=~"cn: ") {
$cn=$_;
$cn=~ s/cn: //g;
}
...
}
What is does:
- It looks for a string inside the line, to see if it contains that particular index
- It then strips off the string and read the rest of the line putting the content into the variable.
- This script reads line by line the result of another script and identify the fields of each line putting the value inside the proper variable

If every line in the list is guaranteed to be in the format 'variableName: someText' then you could do this instead:
foreach (#list) {
/^(\w+): (.*)/ && $vars{$1} = $2;
}
It's not exactly like your solution -- it puts the results into a %vars hash instead of into variables named $cname, $cn, etc. -- but it's more succinct and general.

how about something like this?
my $data = {}; #a hashref to store your data
foreach my $line(#list){
$line =~ s/(givenName|cn|more|names):\s//g and $data->{$1} = $line;
...
}
#EDIT: now you have all your data inside the hashref and can call each var accordingly
print $data->{givenName};
print $data->{cn};

my #list = ('name', 'givenName: ', 'noname');
foreach(#list){
s/givenName: //g if /givenName: /;
my $var = $_;
...
}

Related

In array listitem how to store values with comma separation and end with dot using perl

use strict;
use warnings;
my $tmp = join "\n", <DATA>;
my #biblables = ();
List items will be fetched and storing into #biblables in a while loop
while($tmp=~m/\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/g)
{
push(#biblables, "\\cite{$2}, ");
}
print #biblables;
While printing this we are getting the output like as:
\cite{BuI2001},\cite{BuI2002},\cite{BuI2003},\cite{BuI2004},\cite{BuI2005},\cite{BuI2006},
However we need the output like this
\cite{BuI2001},\cite{BuI2002},\cite{BuI2003},\cite{BuI2004},\cite{BuI2005},\cite{BuI2006}.
Hence we can use post regex to insert dot at the end of the listitem in array
while($tmp=~m/\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/g)
{
my $post = $';
if($post!~m/\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/)
{ push(#biblables, "\\cite{$2}."); }
else { push(#biblables, "\\cite{$2}, "); }
}
print #biblables;
Could you please advise me if there is short way to get this output
#
__DATA__
\bibitem[{BuI (2001)}]{BuI2001}
\bibitem[{BuII (2002)}]{BuI2002}
\bibitem[{BuIII (2003)}]{BuI2003}
\bibitem[{BuIV (2004)}]{BuI2004}
\bibitem[{BuV (2005)}]{BuI2005}
\bibitem[{BuVI (2006)}]{BuI2006}
You can add the comma and period after the fact:
while($tmp=~m/\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/g){
push(#biblables, "\\cite{$2}");
}
print join ', ', #biblables;
print ".\n";
If you read from a filehandle you can use eof to determine that you are on the last line, at which point you replace the comma by the dot in the last element. This allows you to build the array completely in the loop, as required.
use warnings;
use strict;
open my $fh, '<', 'bibitems.txt';
my #biblabels;
while (<$fh>) {
push #biblabels, "\\cite{$2}," if /\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/;
$biblabels[-1] =~ tr/,/./ if eof;
}
print "$_ " for #biblabels;
print "\n";
This prints your desired output.
The oef returns true if the next read will return end-of-file. This means that you've just read the last line, which got put on the array if it matched. This function is rarely needed but here it seems to find a fitting purpose. Note that eof and eof() behave a little differently. Please see the eof page.
If the other capture in the regex is meant to be used change the above to if (...) { ... }. Note that what is in {} is in Latex called citation keys, while the (optional) labels are things inside []. I'd go with the array name of #citkeys for clarity.
If you're determine to add the comma's and dots to the elements when
matching in the regex while loop, it can be done like this.
Since you don't know the total matches yet, just keep a reference to
the most recently pushed element.
Then append the , or . as needed.
Code
use strict;
use warnings;
$/ = undef;
my $tmp = <DATA>;
my #biblables = ();
my $ref = undef;
while( $tmp =~ /\\bibitem\[([^\[\]]*)\]{([^\{\}]*)}/g )
{
$$ref .= ", " if defined $ref;
$ref = \$biblables[ push(#biblables,"\\cite{$2}") ];
}
$$ref .= "." if defined $ref;
print #biblables;
__DATA__
\bibitem[{BuI (2001)}]{BuI2001}
\bibitem[{BuII (2002)}]{BuI2002}
\bibitem[{BuIII (2003)}]{BuI2003}
\bibitem[{BuIV (2004)}]{BuI2004}
\bibitem[{BuV (2005)}]{BuI2005}
\bibitem[{BuVI (2006)}]{BuI2006}
Output
\cite{BuI2001}, \cite{BuI2002}, \cite{BuI2003}, \cite{BuI2004}, \cite{BuI2005}, \cite{BuI2006}.

How to read from specific line to another line - Perl

I'm doing a Perl script and I have a log file where I need to extract data from. I want to know how to read from a specific line to another line(not end of file).
I tried it this way by putting a last if if it reaches the line that I want to stop at but it doesn't work. The line that I want to start reading from is <TEST_HEAD TH 1> and stops at </TEST_HEAD TH 1>. I'm doing this because my regular expression captures data that I do not need, so I tried to read from a specific line to another line.
This is what I've done so far:
while(<$log_fh>)
{
if($. =~ /\<TEST_HEAD TH 1\>/)
{
if ( /Computer Name:\s*(\S+)(-\d+)/i )
{
$details{tester_name} = $1 . $2;
$details{tester_type} = $1;
push #{$details{tester_arr}}, $1 . $2;
}
elsif ( /Operating System:\s*(.*\S)/i )
{
$details{op_sys} = $1;
}
elsif ( /IG-XL Version:\s*([^;]*)/i )
{
$details{igxl_vn} = $1;
}
elsif ( /^([\d]+)\.\d\s+(\S+)\s+([\d-]*)\s+([\d|\w]*)(?=\s)/ )
{
push #{$details{slot}}, $1;
push #{$details{board_name}}, $2;
push #{$details{part_no}}, $3;
push #{$details{serial_no}}, $4;
}
last if $. == /\<\/TEST_HEAD TH 1\>/;
}
}
Just a modified sample of the raw data file:
<TEST_HEAD TH 1> #Start reading here
(Lines containing data to be captured)
</TEST_HEAD TH 1> #end reading here
Without going much into the nested matching logic you may want to change
if($. =~ /\<TEST_HEAD TH 1\>/)
into
if (/<TEST_HEAD TH 1>/ .. /<\/TEST_HEAD TH 1>/)
What you ask is actually XY problem and it would be better to process xml like document with xml parser. Parsing complex XML in Perl
Without knowing specifically how your data looks, I'd also offer another approach.
Set $/ to a record separator, and then you grab a chunk of text in one go. You can then apply a bunch of different regexes to it all at once.
E.g.:
local $/ = 'TEST_HEAD';
while (<$log_fh>) {
next unless m/^\s*TH/;
my ( $tester_name, $tester_id ) = (m/Computer Name:\s*(\S+)(-\d+)/i);
my ($op_sys) = (m/Operating System:\s*(.*\S)/i);
my ( $slot, $board, $part, $serial ) =
(m/^([\d]+)\.\d\s+(\S+)\s+([\d-]*)\s+([\d|\w]*)(?=\s)/m);
# etc.
# then validate and update your array:
$details{$tester_name} = $tester_name;
## etc.
}

Why does my program crash after one line of input?

I am writing a simple program which capitalizes each word in a sentence. It gets a multi-line input. I then loop through the input lines, split each word in the line, capitalize it and then join the line again. This works fine if the input is one sentence, but as soon as I input two lines my program crashes (and if I wait too long my computer freezes.)
Here is my code
#input = <STDIN>;
foreach(#input)
{
#reset #words
#words= ();
#readability
$lines =$_;
#split sentence
#words = split( / /, $lines );
#capitalize each word
foreach(#words){
$words[$k] = ucfirst;
$k++;
}
#join sentences again
$lines = join(' ', #words);
#create output line
$output[$i]=$lines;
$i++;
}
#print the result
print "\nResult:\n";
foreach(#output){
print $output[$j],"\n";
$j++;
}
Could someone please tell me why it crashes?
use strict (and be told about not properly handled variables like your indices)
use for var (array) to get a usable item without an index (Perl isn't Javascript)
What isn't there can't be wrong (e.g. push instead of index)
In code:
use strict; # always!
my #input = <STDIN>; # the loop need in- and output
my #output = ();
for my $line (#input) # for makes readability *and* terseness easy
{
chomp $line; # get rid of eol
#split sentence
my #words = split( / /, $line );
#capitalize each word
for my $word (#words){ # no danger of mishandling indices
$word = ucfirst($word);
}
#join sentences again
$line = join(' ', #words);
#create output line
push #output, $line;
}
#print the result
print "\nResult:\n";
for my $line (#output){
print $line, "\n";
}
The problem is that you are using global variables throughout, so they are keeping their values across iterations of the loop. You have reset #words to an empty list even though you didn't need to - it is overwritten when you assign the result of split to it - but $k is increasing endlessly.
$k is initially set to undef which evaluates as zero, so for the first sentence everything is fine. But you leave $k set to the number of elements in #words so it starts from there instead of from zero for the next sentence. Your loop over #words becomes endless because you are assigning to (and so creating) $words[$k] so the array is getting longer as fast as you are looping through it.
The same problem applies to $i and $j, but execution never gets as far as reusing those.
Alshtough this was the only way of working in Perl 4, over twenty years ago, Perl 5 has made programming very much nicer to write and debug. You can now declare variables with my, and you can use strict which (among other things) insists that every variable you use must be declared, otherwise your program won't compile. There is also use warnings which is just as invaluable. In this case it would have warned you that you were using an undefined variable $k etc. to index the arrays.
If I apply use strict and use warnings, declare all of your variables and initialise the counters to zero then I get a working program. It's still not very elegant, and there are much better ways of doing it, but the error has gone away.
use strict;
use warnings;
my #input = <STDIN>;
my #output;
my $i = 0;
foreach (#input) {
# readability
my $lines = $_;
# split sentence
my #words = split ' ', $lines;
# capitalize each word
my $k = 0;
foreach (#words) {
$words[$k] = ucfirst;
$k++;
}
# join sentences again
$lines = join ' ', #words;
#create output line
$output[$i] = $lines;
$i++;
}
print "\nResult:\n";
my $j = 0;
foreach (#output) {
print $output[$j], "\n";
$j++;
}

regular expression code

I need to find match between two tab delimited files files like this:
File 1:
ID1 1 65383896 65383896 G C PCNXL3
ID1 2 56788990 55678900 T A ACT1
ID1 1 56788990 55678900 T A PRO55
File 2
ID2 34 65383896 65383896 G C MET5
ID2 2 56788990 55678900 T A ACT1
ID2 2 56788990 55678900 T A HLA
what I would like to do is to retrive the matching line between the two file. What I would like to match is everyting after the gene ID
So far I have written this code but unfortunately perl keeps giving me the error:
use of "Use of uninitialized value in pattern match (m//)"
Could you please help me figure out where i am doing it wrong?
Thank you in advance!
use strict;
open (INA, $ARGV[0]) || die "cannot to open gene file";
open (INB, $ARGV[1]) || die "cannot to open coding_annotated.var files";
my #sample1 = <INA>;
my #sample2 = <INB>;
foreach my $line (#sample1) {
my #tab = split (/\t/, $line);
my $chr = $tab[1];
my $start = $tab[2];
my $end = $tab[3];
my $ref = $tab[4];
my $alt = $tab[5];
my $name = $tab[6];
foreach my $item (#sample2){
my #fields = split (/\t/,$item);
if ( $fields[1] =~ m/$chr(.*)/
&& $fields[2] =~ m/$start(.*)/
&& $fields[4] =~ m/$ref(.*)/
&& $fields[5] =~ m/$alt(.*)/
&& $fields[6] =~ m/$name(.*)/
) {
print $line, "\n", $item;
}
}
}
On its surface your code seems to be fine (although I didn't debug it). If you don't have an error I cannot spot, could be that the input data has RE special character, which will confuse the regular expression engine when you put it as is (e.g. if any of the variable has the '$' character). Could also be that instead of tab you have spaces some where, in which case you'll indeed get an error, because your split will fail.
In any case, you'll be better off composing just one regular expression that contains all the fields. My code below is a little bit more Perl Idiomatic. I like using the implicit $_ which in my opinion makes the code more readable. I just tested it with your input files and it does the job.
use strict;
open (INA, $ARGV[0]) or die "cannot open file 1";
open (INB, $ARGV[1]) or die "cannot open file 2";
my #sample1 = <INA>;
my #sample2 = <INB>;
foreach (#sample1) {
(my $id, my $chr, my $start, my $end, my $ref, my $alt, my $name) =
m/^(ID\d+)\s+(\w+)\s+(\w+)\s+(\w+)\s+(\w+)\s+(\w+)\s+(\w+)/;
my $rex = "^ID\\d+\\s+$chr\\s+$start\\s+$end\\s+$ref\\s+$alt\\s+$name\\s+";
#print "$rex\n";
foreach (#sample2) {
if( m/$rex/ ) {
print "$id - $_";
}
}
}
Also, how regular is the input data? Do you have exactly one tab between the fields? If that is the case, there is no point to split the lines into 7 different fields - you only need two: the ID portion of the line, and the rest. The first regex would be
(my $id, my $restOfLine) = m/^(ID\d+)\s+(.*)$/;
And you are searching $restOfLine within the second file in a similar technique as above.
If your files are huge and performance is an issue, you should consider putting the first regular expressions (or strings) in a map. That will give you O(n*log(m)) where n and m are the number of lines in each file.
Finally, I have a similar challenge when I need to compare logs. The logs are supposed to be identical, with the exception of a time mark at the beginning of each line. But more importantly: most lines are the same and in order. If this is what you have, and it make sense for you, you can:
First remove the IDxxx from each line: perl -pe "s/ID\d+ +//" file >cleanfile
Then use BeyondCompare or Windiff to compare the files.
I played a bit with your code. What you wrote there was actually three loops:
one over the lines of the first file,
one over the lines of the second file, and
one over all fields in these lines. You manually unrolled this loop.
The rest of this answer assumes that the files are strictly tab-seperated and that any other whitespace matters (even at the end of fields and lines).
Here is a condensed version of the code (assumes open filehandles $file1, $file2, and use strict):
my #sample2 = <$file2>;
SAMPLE_1:
foreach my $s1 (<$file1>) {
my (undef, #fields1) = split /\t/, $s1;
my #regexens = map qr{\Q$_\E(.*)}, #fields1;
SAMPLE_2:
foreach my $s2 (#sample2) {
my (undef, #fields2) = split /\t/, $s2;
for my $i (0 .. $#regexens) {
$fields2[$i] =~ $regexens[$i] or next SAMPLE_2;
}
# only gets here if all regexes matched
print $s1, $s2;
}
}
I did some optimisations: precompiling the various regexes and storing them in an array, quoting the contents of the fields etc. However, this algorithm is O(n²), which is bad.
Here is an elegant variant of that algorithm that knows that only the first field is different — the rest of the line has to be the same character for character:
my #sample2 = <$file2>;
foreach my $s1 (<$file1>) {
foreach my $s2 (#sample2) {
print $s1, $s2 if (split /\t/, $s1, 2)[1] eq (split /\t/, $s2, 2)[1];
}
}
I just test for string equality of the rest of the line. While this algorithm is still O(n²), it outperforms the first solution roughly by an order of magnitude simply by avoiding braindead regexes here.
Finally, here is an O(n) solution. It is a variant of the previous one, but executes the loops after each other, not inside each other, therefore finishing in linear time. We use hashes:
# first loop via map
my %seen = map {reverse(split /\t/, $_, 2)}
# map {/\S/ ? $_ : () } # uncomment this line to handle empty lines
<$file1>;
# 2nd loop
foreach my $line (<$file2>) {
my ($id2, $key) = split /\t/, $line, 2;
if (defined (my $id1 = $seen{$key})) {
print "$id1\t$key";
print "$id2\t$key";
}
}
%seen is a hash that has the rest of the line as a key and the first field as a value. In the second loop, we retrieve the rest of the line again. If this line was present in the first file, we reconstruct the whole line and print it out. This solution is better than the others and scales well up- and downwards, because of its linear complexity
How about:
#!/usr/bin/perl
use File::Slurp;
use strict;
my ($ina, $inb) = #ARGV;
my #lines_a = File::Slurp::read_file($ina);
my #lines_b = File::Slurp::read_file($inb);
my $table_b = {};
my $ln = 0;
# Store all lines in second file in a hash with every different value as a hash key
# If there are several identical ones we store them also, so the hash values are lists containing the id and line number
foreach (#lines_b) {
chomp; # strip newlines
$ln++; # count current line number
my ($id, $rest) = split(m{[\t\s]+}, $_, 2); # split on whitespaces, could be too many tabs or spaces instead
if (exists $table_b->{$rest}) {
push #{ $table_b->{$rest} }, [$id, $ln]; # push to existing list if we already found an entry that is the same
} else {
$table_b->{$rest} = [ [$id, $ln] ]; # create new entry if this is the first one
}
}
# Go thru first file and print out all matches we might have
$ln = 0;
foreach (#lines_a) {
chomp;
$ln++;
my ($id, $rest) = split(m{[\t\s]+}, $_, 2);
if (exists $table_b->{$rest}) { # if we have this entry print where it is found
print "$ina:$ln:\t\t'$id\t$rest'\n " . (join '\n ', map { "$inb:$_->[1]:\t\t'$_->[0]\t$rest'" } #{ $table_b->{$rest} }) . "\n";
}
}

Is there any better way to "grep" from a large file than using `grep` in perl?

The $rvsfile is the path of a file about 200M. I want to count the number of line which has $userid in it. But using grep in a while loop seems very slowly. So is there any efficient way to do this? Because the $rvsfile is very large, I can't read it into memory using #tmp = <FILEHANDLE>.
while(defined($line = <SRCFILE>))
{
$line =~ /^([^\t]*)\t/;
$userid = $1;
$linenum = `grep '^$userid\$' $rvsfile | wc -l`;
chomp($linenum);
print "$userid $linenum\n";
if($linenum == 0)
{
print TARGETFILE "$line";
}
}
And how can I get the part before \t in a line without regex? For example, the line may like this:
2013123\tsomething
How can I get 2013123 without regex?
Yes, you are forking a shell on each loop invocation. This is slow. You also read the entire $rsvfile once for every user. This is too much work.
Read SRCFILE once and build a list of #userids.
Read $rvsfile once keeping a running count of each user id as you go.
Sketch:
my #userids;
while(<SRCFILE>)
{
push #userids, $1 if /^([^\t]*)\t/;
}
my $regex = join '|', #userids;
my %count;
while (<RSVFILE>)
{
++$count{$1} if /^($regex)$/o
}
# %count has everything you need...
Use hashes:
my %count;
while (<LARGEFILE>) {
chomp;
$count{$_}++;
};
# now $count{userid} is the number of occurances
# of $userid in LARGEFILE
Or if you fear using too much memory for the hash (i.e. you're interested in 6 users, and there are 100K more in the large file), do it another way:
my %count;
while (<SMALLFILE>) {
/^(.*?)\t/ and $count{$_} = 0;
};
while (<LARGEFILE>) {
chomp;
$count{$_}++ if defined $count{$_};
};
# now $count{userid} is the number of occurances
# of $userid in LARGEFILE, *if* userid is in SMALLFILE
You can search for the location of the first \t using index which will be faster. You could then use splice to get the match.
Suggest you benchmark various approaches.
If I read you correctly you want something like this:
#!/usr/bin/perl
use strict;
use warnings;
my $userid = 1246;
my $count = 0;
my $rsvfile = 'sample';
open my $fh, '<', $rsvfile;
while(<$fh>) {
$count++ if /$userid/;
}
print "$count\n";
or even, (and someone correct me if I am wrong, but this don't think this reads the whole file in):
#!/usr/bin/perl
use strict;
use warnings;
my $userid = 1246;
my $rsvfile = 'sample';
open my $fh, '<', $rsvfile;
my $count = grep {/$userid/} <$fh>;
print "$count\n";
If <SRCFILE> is relatively small, you could do it the other way round. Read in the larger file one line at a time, and check each userid per line, keeping a count of each userid using a hash sructure. Something like:
my %userids = map {($_, 0)} # use as hash key with init value of 0
grep {$_} # only return mataches
map {/^([^\t]+)/} <SRCFILE>; # extract ID
while (defined($line = <LARGEFILE>)) {
for (keys %userids) {
++$userids{$_} if $line =~ /\Q$_\E/; # \Q...\E escapes special chars in $_
}
}
This way, only the smaller data is read repeatedly and the large file is scanned once. You end up with a hash of every userid, and the value is the number of lines it occurred in.
if you have a choice, try it with awk
awk 'FNR==NR{a[$1];next} { for(i in a) { if ($0 ~ i) { print $0} } } ' $SRCFILE $rsvfile