I'm trying to find and extract the occurrence of words read from a text file in a text file. So far I can only find when the word is written correctly and not munged (a changed to # or i changed to 1). Is it possible to add a regex to my strings for matching or something similar? This is my code so far:
sub getOccurrenceOfStringInFileCaseInsensitive
{
my $fileName = $_[0];
my $stringToCount = $_[1];
my $numberOfOccurrences = 0;
my #wordArray = wordsInFileToArray ($fileName);
foreach (#wordArray)
{
my $numberOfNewOccurrences = () = (m/$stringToCount/gi);
$numberOfOccurrences += $numberOfNewOccurrences;
}
return $numberOfOccurrences;
}
The routine receives the name of a file and the string to search. The routine wordsInFileToArray () just gets every word from the file and returns an array with them.
Ideally I would like to perform this search directly reading from the file in one go instead of moving everything to an array and iterating through it. But the main question is how to hard code something into the function that allows me to capture munged words.
Example: I would like to extract both lines from the file.
example.txt:
russ1#anh#ck3r
russianhacker
# this variable also will be read from a blacklist file
$searchString = "russianhacker";
getOccurrenceOfStringInFileCaseInsensitive ("example.txt", $searchString);
Thanks in advance for any responses.
Edit:
The possible substitutions will be defined by an user and the regex must be set to fit. A user could say that a common substitution is to change the letter "a" to "#" or even "1". The possible change is completely arbitrary.
When searching for a specific word ("russian" for example) this could be done with something like:
(m/russian/i); # would just match the word as it is
(m/russi[a#1]n/i); # would match the munged word
But I'm not sure how to do that if I have the string to match stored in a variable, such as:
$stringToSearch = "russian";
This is sort of a full-text search problem, so one method is to normalize the document strings before matching against them.
use strict;
use warnings;
use Data::Munge 'list2re';
...
my %norms = (
'#' => 'a',
'1' => 'i',
...
);
my $re = list2re keys %norms;
s/($re)/$norms{$1}/ge for #wordArray;
This approach only works if there's only a single possible "normalized form" for any given word, and may be less efficient anyway than just trying every possible variation of the search string if your document is large enough and you recompute this every time you search it.
As a note your regex m/$randomString/gi should be m/\Q$randomString/gi, as you don't want any regex metacharacters in $randomString to be interpreted that way. See docs for quotemeta.
There are parts of the problem which aren't specified precisely enough (yet).
Some of the roll-your-own approaches, that depend on the details, are
If user defined substitutions are global (replace every occurrence of a character in every string) the user can submit a mapping, as a hash say, and you can fix them all. The process will identify all candidates for the words (along with the actual, unmangled, words, if found). There may be false positives so also plan on some post-processing
If the user can supply a list of substitutions along with words that they apply to (the mangled or the corresponding unmangled ones) then we can have a more targeted run
Before this is clarified, here is another way: use a module for approximate ("fuzzy") matching.
The String::Approx seems to fit quite a few of your requirements.
The match of the target with a given string relies on the notion of the Levenshtein edit distance: how many insertions, deletions, and replacements ("edits") it takes to make the given string into the sought target. The maximum accepted number of edits can be set.
A simple-minded example:
use warnings;
use strict;
use feature 'say';
use String::Approx qw(amatch);
my $target = qq(russianhacker);
my #text = qw(that h#cker was a russ1#anh#ck3r);
my #matches = amatch($target, ["25%"], #text);
say for #matches; #==> russ1#anh#ck3r
See documentation for what the module avails us, but at least two comments are in place.
First, note that the second argument in amatch specifies the percentile-deviation from the target string that is acceptable. For this particular example we need to allow every fourth character to be "edited." So much room for tweaking can result in accidental matches which then need be filtered out, so there will be some post-processing to do.
Second -- we didn't catch the easier one, h#cker. The module takes a fixed "pattern" (target), not a regex, and can search for only one at a time. So, in principle, you need a pass for each target string. This can be improved a lot, but there'll be more work to do.
Please study the documentation; the module offers a whole lot more than this simple example.
I've ended solving the problem by including the regex directly on the variable that I'll use to match against the lines of my file. It looks something like this:
sub getOccurrenceOfMungedStringInFile
{
my $fileName = $_[0];
my $mungedWordToCount = $_[1];
my $numberOfOccurrences = 0;
open (my $inputFile, "<", $fileName) or die "Can't open file: $!";
$mungedWordToCount =~ s/a/\[a\#4\]/gi;
while (my $currentLine = <$inputFile>)
{
chomp ($currentLine);
$numberOfOccurrences += () = ($currentLine =~ m/$mungedWordToCount/gi);
}
close ($inputFile) or die "Can't open file: $!";
return $numberOfOccurrences;
}
Where the line:
$mungedWordToCount =~ s/a/\[a\#4\]/gi;
Is just one of the substitutions that are needed and others can be added similarly.
I didn't know that Perl would just interpret the regex inside of the variable since I've tried that before and could only get the wanted results defining the variables inside the function using single quotes. I must've done something wrong the first time.
Thanks for the suggestions, people.
I have a file I need to take just its name:
/var/www/foo/dog.tur-tles.chickens.txt
I want to match just the:
dog.tur-tles.chickens
I have tried this in regexer:
([^\/]*)$
This matches:
dog.tur-tles.chickens.txt
I can't figure out how to only exclude that last period.
You can assume it will always be a .txt, but I wanted to build in the ability that if a file was named dog-turtles.txt.txt it would see that the name is dog-turtles.txt.
You could use something like so: ([^\/]*)(\.).+?$.
An example is available here. Not though that this will fail for extensions such as .tar.gz and so on.
You may use File::Basename.fileparse to get the file name, then use rindex to get the last index of . and then get the required substring using substr:
use File::Basename;
$x = fileparse('/var/www/foo/dog.tur-tles.chickens.txt');
print substr($x, 0, rindex($x, '.')) . "\n";
Output of a sample program:
dog.tur-tles.chickens
$name = ($pathname =~ s{.*/}{}r =~ s{\.[^.]+$}{}r)
substitution 1 : just remove dir
substitution 2 : just remove extension if presente
Just add .txt to your regex and since * is greedy by default it will match everything till last .txt
([^\/]*)\.txt$
Input:
/var/www/foo/dog.tur-tles.chickens.txt.txt
/var/www/foo/dog.tur-tles.chickens.txt
Output:
dog.tur-tles.chickens.txt
dog.tur-tles.chickens
See DEMO
I've got a function in Perl that reads the last modified .csv in a folder, and parses it's values into variables.
I'm finding some problems with the regular expressions.
My .csv look like:
Title is: "NAME_NAME_NAME"
"Period end","Duration","Sample","Corner","Line","PDP OUT TOTAL","PDP OUT OK","PDP OUT NOK","PDP OUT OK Rate"
"04/12/2014 11:00:00","3600","1","GPRS_OUT","ARG - NAME 1","536","536","0","100%"
"04/12/2014 11:00:00","3600","1","GPRS_OUT","USA - NAME 2","1850","1438","412","77.72%"
"04/12/2014 11:00:00","3600","1","GPRS_OUT","AUS - NAME 3","8","6","2","75%"
.(ignore this dot, you will understand later)
So far, I've had some help to parse the values into some variables, by:
open my $file, "<", $newest_file
or die qq(Cannot open file "$newest_file" for reading.);
while ( my $line = <$file> ) {
my ($date_time, $duration, $sample, $corner, $country_name, $pdp_in_total, $pdp_in_ok, $pdp_in_not_ok, $pdp_in_ok_rate)
= parse_line ',', 0, $line;
my ($date, $time) = split /\s+/, $date_time;
my ($country, $name) = $country_name =~ m/(.+) - (.*)/;
print "$date, $time, $country, $name, $pdp_in_total, $pdp_in_ok_rate";
}
The problems are:
I don't know how to make the first AND second line (that are the column names from the .csv) to be ignored;
The file sometimes come with 2-5 empty lines in the end of the file, as I show in my sample (ignore the dot in the end of it, it doesn't exists in the file).
How can I do this?
When you have a csv file with column headers and want to parse the data into variables, the simplest choice would be to use Text::CSV. This code shows how you get your data into the hash reference $row. (I.e. my %data = %$row)
use strict;
use warnings;
use Text::CSV;
use feature 'say';
my $csv = Text::CSV->new({
binary => 1,
eol => $/,
});
# open the file, I use the DATA internal file handle here
my $title = <DATA>;
# Set the headers using the header line
$csv->column_names( $csv->getline(*DATA) );
while (my $row = $csv->getline_hr(*DATA)) {
# you can now access the variables via their header names, e.g.:
if (defined $row->{Duration}) { # this will skip the blank lines
say $row->{Duration};
}
}
__DATA__
Title is: "NAME_NAME_NAME"
"Period end","Duration","Sample","Corner","Line","PDP IN TOTAL","PDP IN OK","PDP IN NOT OK","PDP IN OK Rate"
"04/12/2014 10:00:00","3600","1","GRPS_INB","CHN - Name 1","1198","1195","3","99.74%"
"04/12/2014 10:00:00","3600","1","GRPS_INB","ARG - Name 2","1198","1069","129","89.23%"
"04/12/2014 10:00:00","3600","1","GRPS_INB","NLD - Name 3","813","798","15","98.15%"
If we print one of the $row variables with Data::Dumper, it shows the structure we are getting back from Text::CSV:
$VAR1 = {
'PDP IN TOTAL' => '1198',
'PDP IN NOT OK' => '3',
'PDP IN OK' => '1195',
'Period end' => '04/12/2014 10:00:00',
'Line' => 'CHN - Name 1',
'Duration' => '3600',
'Sample' => '1',
'PDP IN OK Rate' => '99.74%',
'Corner' => 'GRPS_INB'
};
open ...
my $names_from_first_line = <$file>; # you can use them or just ignore them
while($my line = <$file>) {
unless ($line =~ /\S/) {
# skip empty lines
next;
}
..
}
Also, consider using Text::CSV to handle CSV format
1) I don't know how to make the first line (that are the column names from the .csv) to be ignored;
while ( my $line = <$file> ) {
chomp $line;
next if $. == 1 || $. == 2;
2) The file sometimes come with 2-5 empty lines in the end of the file, as I show in my sample (ignore the dot in the end of it, it doesn't exists in the file).
while ( my $line = <$file> ) {
chomp $line;
next if $. == 1 || $. == 2;
next if $line =~ /^\s*$/;
You know that the valid lines will start with dates. I suggest you simply skip lines that don't start with dates in the format you expect:
while ( my $line = <$file> ) {
warn qq(next if not $line =~ /^"\d{2}-\d{2}-d{4}/;); # Temp debugging line
next if not $line =~ /^"\d{2}-\d{2}-d{4}/;
warn qq($line matched regular expression); # Temp debugging line
...
}
The /^"\d{2}-\d{2}-d{4}",/ is a regular expression pattern. The pattern is between the /.../:
^ - Beginning of the line.
" - Quotation Mark.
\d{2} - Followed by two digits.
- - Followed by a dash.
\d{2] - Followed by two more digits.
- - Followed by a dash.
\d{4} - Followed by four more digits
This should be describing the first part of your line which is the date in MM-DD-YYYY format surrounded by quotes and followed by a comma. The =~ tells Perl that you want the thing on the left to match the regular expression on the right.
Regular expressions can be difficult to understand, and is one of the reasons why Perl has such a reputation of being a write-only language. Regular expressions have been likened to sailor cussing. However, regular expressions is an extremely powerful tool, and worth the effort to learn. And with some experience, you'll be able to easily decode them.
The next if... syntax is similar to:
if (...) {
next;
}
Normally, you shouldn't use post-fix if and never use unless (which is if's opposite). They can make your program more difficult to understand. However, when placed right after the opening line of a loop like this, they make a clear statement that you're filtering out lines you don't want. I could have written this (and many people would argue this is preferable):
next unless $line =~ /^"\d{2}-\d{2}-d{4}",/;
This is saying you want to skip lines unless they match your regular expression. It's all a matter of personal preference and what do you think is easier for the poor schlub who comes along next year and has to figure out what your program is doing.
I actually thought about this and decided that if not ... was saying that I expect almost all lines in the file to match my format, and I want to toss away the few exceptions. To me, next unless ... is saying that there are some lines that match my regular expression, and many lines that don't, and I want to only work on lines that match.
Which gets us to the next part of programming: Watching for things that will break your program. My previous answer didn't do a lot of error checking, but it should. What happens if a line doesn't match your format? What if the split didn't work? What if the fields are not what I expect? You should really check each statement to make sure it actually worked. Almost all functions in Perl will return a zero, a null string, or an undef if they don't work. For example, the open statement.
open my $file, "<", $newest_file
or die qq(Cannot open file "$newest_file" for reading.);
If open doesn't work, it returns a file handle value of zero. The or states that if open doesn't return a non-zero file handle, execute the line that follows which kills your program.
So, look through your program, and see any place where you make an assumption that something works as expected and think what happens if it didn't. Then, add checks in your program to something if you get that exception. It could be that you want to report the error or log the error and skip to the next line. It could be that you want your program to come to a screeching halt. It could be that you can recover from the error and continue. What ever you do, check for possible errors (especially from user input) and handle possible errors.
Debugging
I told you regular expressions are tricky. Yes, I made a mistake assuming that your date was a separate field. Instead, it's followed by a space then the time which means that the final ", in the regular expression should not be there. I've fixed the above code. However, you may still need to test and tweak. Which brings us into debugging in Perl.
You can use warn statements to help debug your program. If you copy a statement, then surround it with warn qq(...);, Perl will print out the line (filling out variables) and the line number. I even create macros in my various editors to do this for me.
The qq(...) is a quote like operator. It's another way to do double quotes around a string. The nice thing is that the string can contain actual quotation marks, and the qq(...); will still work.
Once you've finished debugging, you can search for your warn statements and delete them. Perl comes with a powerful built in debugger, and many IDEs integrate with it. However, sometimes it's just easier to toss in a few warn statements to see what's going on in your code -- especially if you're having issues with regular expressions acting up.
Okay, so I'm using perl to read in a file that contains some general configuration data. This data is organized into headers based on what they mean. An example follows:
[vars]
# This is how we define a variable!
$var = 10;
$str = "Hello thar!";
# This section contains flags which can be used to modify module behavior
# All modules read this file and if they understand any of the flags, use them
[flags]
Verbose = true; # Notice the errant whitespace!
[path]
WinPath = default; # Keyword which loads the standard PATH as defined by the operating system. Append with additonal values.
LinuxPath = default;
Goal: Using the first line as an example "$var = 10;", I'd like to use the split function in perl to create an array that contains the characters "$var" and "10" as elements. Using another line as an example:
Verbose = true;
# Should become [Verbose, true] aka no whitespace is present
This is needed because I will be outputting these values to a new file (which a different piece of C++ code will read) to instantiate dictionary objects. Just to give you a little taste of what it might look like (just making it up as I go along):
define new dictionary
name: [flags]
# Start defining keys => values
new key name: Verbose
new value val: 10
# End dictionary
Oh, and here is the code I currently have along with what it is doing (incorrectly):
sub makeref($)
{
my #line = (split (/=/)); # Produces ["Verbose", " true"];
}
To answer one question, why I am not using Config::Simple, is that I originally did not know what my configuration file would look like, only what I wanted it to do. Making it up as I went along - at least what seemed sensible to me - and using perl to parse the file.
The problem is I have some C++ code that will load the information in the config file, but since parsing in C or C++ is :( I decided to use perl. It's also a good learning exercise for me since I am new to the language. So that's the thing, this perl code is not really apart of my application, it just makes it easier for the C++ code to read the information. And, it is more readable (both the config file, and the generated file). Thanks for the feedback, it really helped.
If you're doing this parsing as a learning exercise, that's fine. However, CPAN has several modules that will do a lot of the work for you.
use Config::Simple;
Config::Simple->import_from( 'some_config_file.txt', \my %conf );
split splits on a regular expression, so you can simply put the whitespace around the = sign into its regex:
split (/\s*=\s*/, $line);
You obviously do not want to remove all whitespace, or such a line would be produced (whitespace missing in the string):
$str="Hellothere!";
I guess that only removing whitespace from the beginning and end of the line is sufficient:
$line =~ s/^\s*(.*?)\s*$/$1/;
A simpler alternative with two statements:
$line =~ s/^\s+//;
$line =~ s/\s+$//;
Seems like you've got it. Strip the whitespaces before splitting.
sub makeref($)
{
s/\s+//g;
my #line = (split(/=/)); # gets ["verbose", "true"]
}
This code does the trick (and is more efficient without reversing).
for (#line) {
s/^\s+//;
s/\s+$//;
}
You probably have it all figured out, but I thought I'd add a little. If you
sub makeref($)
{
my #line = (split(/=/));
foreach (#line)
{
s/^\s+//g;
s/\s+$//g;
}
}
then you will remove the whitespace before and after both the left and right side. That way something like:
this is a parameter = all sorts of stuff here
will not have crazy spaces.
!!Warning: I probably don't know what I'm talking about!!
I need to separate out a bunch of image urls from a document in which the images are associated with names like this:
bellpepper = "http://images.com/bellpepper.jpg"
cabbage = "http://images.com/cabbage.jpg"
lettuce = "http://images.com/lettuce.jpg"
pumpkin = "http://images.com/pumpkin.jpg"
I assume I can detect the start of a link with:
/http:[^ ,]+/i
But how can I get all of the links separated from the document?
EDIT: To clarify the question: I just want to strip out the URLs from the file minus the variable name, equals sign and double quotes so I have a new file that is just a list of URLs, one per line.
Try this...
(http://)([a-zA-Z0-9\/\\.])*
If the format is constant, then this should work (python):
import re
s = """bellpepper = "http://images.com/bellpepper.jpg" (...) """
re.findall("\"(http://.+?)\"", s)
Note: this is not "find an image in a file" regexp, just an answer to the question :)
do you mean to say you have that kind of format in your document and you just want to get the http part? you can just split on the "=" delimiter without regex
$f = fopen("file","r");
if ($f){
while( !feof($f) ){
$line = fgets($f,4096);
$s = explode(" = ",$line);
$s = preg_replace("/\"/","",$s);
print $s[1];
}
fclose($f);
}
on the command line :
#php5 myscript.php > newfile.ext
if you are using other languages other than PHP, there are similar string splitting method you can use. eg Python/Perl's split(). please read your doc to find out
You may try this, if your tool supports positive lookbehind:
/(?<=")[^"\n]+/