I've run into a text processing problem. I've an article, and I'd like to find out how many "real" words there are.
Here is what I mean by "real". Articles usually contain various punctuation marks such as dashes, and commas, dots, etc. What I'd like to find out is how many words there are, skipping like "-" dashes and "," commas with spaces, etc.
I tried doing this:
my #words = split ' ', $article;
print scalar #words, "\n";
But that includes various punctuations that have spaces in them as words.
So I'm thinking of using this:
my #words = grep { /[a-z0-9]/i } split ' ', $article;
print scalar #words, "\n";
This would match all words that have characters or numbers in them. What do you think, would this be good enough way to count words in an article?
Does anyone know maybe of a module on CPAN that does this?
Try to use: \W - any non-word character, and also drop _
Solution
use strict;
my $article = 'abdc, dd_ff, 11i-11, ff44';
# case David's, but it didn't work with I'm or There's
$article =~ s/\'//g;
my $number_words = scalar (split /[\W_]+/, $article);
print $number_words;
I think your solution is about as good as you're going to get without resorting to something elaborate.
You could also write it as
my #words = $article =~ /\S*\w\S*/
or count the words in a file by writing
my $n = 0;
while (<>) {
my #words = /\S*\w\S*/g;
$n += #words;
}
say "$n words found";
Try a few sample blocks of text and look at the list of "words" that it finds. If you are happy with that then your code works.
Related
I'm using Perl to feed data to an LCD display. The display is 8 characters wide. The strings of data to be displayed are always significantly longer than 8 characters. As such, I need to break the strings down into "frames" of 8 characters or less, and feed the "frames" to the display one at a time.
The display is not intelligent enough to do this on its own. The only convenience it offers is that strings of less than 8 characters are automatically centered on the display.
In the beginning, I simply sent the string 8 characters at a time - here goes 1-8, now 9-16, now 17-24, etc. But that wasn't especially nice-looking. I'd like to do something better, but I'm not sure how best to approach it.
These are the constraints I'd like to implement:
Fit as many words into a "frame" as possible
No starting/trailing space(s) in a "frame"
Symbol (ie. hyphen, ampersand, etc) with a space on both sides qualifies as a word
If a word is longer than 8 characters, simulate per-character scrolling
Break words longer than 8 characters at a slash or hyphen
Some hypothetical input strings, and desired output for each...
Electric Light Orchestra - Sweet Talkin' Woman
Electric
Light
Orchestr
rchestra
- Sweet
Talkin'
Woman
Quarterflash - Harden My Heart
Quarterf
uarterfl
arterfla
rterflas
terflash
- Harden
My Heart
Steve Miller Band - Fly Like An Eagle
Steve
Miller
Band -
Fly Like
An Eagle
Hall & Oates - Did It In A Minute
Hall &
Oates -
Did It
In A
Minute
Bachman-Turner Overdrive - You Ain't Seen Nothing Yet
Bachman-
Turner
Overdriv
verdrive
- You
Ain't
Seen
Nothing
Yet
Being a relative Perl newbie, I'm trying to picture how would be best to handle this. Certainly I could split the string into an array of individual words. From there, perhaps I could loop through the array, counting the letters in each subsequent word to build the 8-character "frames". Upon encountering a word longer than 8 characters, I could then repetitively call substr on that word (with offset +1 each time), creating the illusion of scrolling.
Is this a reasonable way to accomplish my goal? Or am I reinventing the wheel here? How would you do it?
The base question is to find all consecutive overlapping N-long substrings in a compact way.
Here it is in one pass with a regex, and see the end for doing it using substr.
my $str = join '', "a".."k"; # 'Quarterflash';
my #eights = $str =~ /(?=(.{8}))/g;
This uses a lookahead which also captures, and in this way the regex crawls up the string character by character, capturing the "next" eight each time.
Once we are at it, here is also a basic solution for the problem. Add words to a buffer until it would exceed 8 characters, at which point it is added to an array of display-ready strings and cleared.
use warnings;
use strict;
use feature 'say';
my $str = shift // "Quarterflash - Harden My Heart";
my #words = split ' ', $str;
my #to_display;
my $buf = '';
foreach my $w (#words) {
if (length $w > 8) {
# Now have to process the buffer first then deal with this long word
push #to_display, $buf;
$buf = '';
push #to_display, $w =~ /(?=(.{8}))/g;
}
elsif ( length($buf) + 1 + length($w) > 8 ) {
push #to_display, $buf;
$buf = $w;
}
elsif (length $buf != 0) { $buf .= ' ' . $w }
else { $buf = $w }
}
push #to_display, $buf if $buf;
say for #to_display;
This is clearly missing some special/edge cases, in particular those involving non-word characters and hyphenated words, but that shouldn't be too difficult to add.†
Here is a way to get all consecutive 8-long substrings using substr
my #to_display = map { substr $str, $_, 8 } 0..length($str)-8;
† Example, break a word with hyphen/slash when it has no spaces around it (per question)
my #parts = split m{\s+|(?<=\S)[-/](?=\S)}, $w;
The hyphen/slash is discarded as this stands; that can be changed by capturing the pattern as well and then filtering out elements with only spaces
my #parts = grep { /\S/ } split m{( \s+ | (?<=\S) [-/] (?=\S) )}x, $w;
These haven't been tested beyond just barely. Can fit in the if (length $w > 8) branch.
The initial take-- The regex was originally written with a two-part pattern. Keeping it here for record and as an example of use of pair-handling functions from List::Util
The regex below matches and captures a character, followed by a lookahead for the next seven, which it also captures. This way the engine captures 1 and 7-long substrings as it moves along char by char. Then the consecutive pairs from the returned list are joined
my $str = join '', "a".."k"; # 'Quarterflash';
use List::Util qw(pairmap);
my #eights = pairmap { $a . $b } $str =~ /(. (?=(.{7})) )/gx;
# or
# use List::Util qw(pairs);
# my #eights = map { join '', #$_ } pairs $str =~ /(.(?=(.{7})))/g;
$text = "I like apples more than oranges\n";
#words = split /” “/, $text;
foreach (#words) [1..] {
if $words "AEIOUaeiou";
$words =~ tr/A E I O U a e i o u//d;
}
print "$words\n";
"I like apples more than oranges" will become "I lk appls mr thn orngs". "I" in "I", "a" in "appls" and "o" in "orngs" will stay because they are the first letter in the word.
This is my research assignment as a first year student. I am allowed to ask questions and later cite them. Please don't be mean.
I know you say you are not allowed to use a regex, but for everyone else that shows up here I'll show the use of proper tools. But, then I'll do something just as useful with tr///.
One of the tricks of programming (and mathematics) decomposing what look like hard problems into easier problems, especially if you already have solutions for the easy problems. (Read about Parnas decomposition, for example).
So, the question is "How can I remove all the vowels unless they are in word beginnings?" (after I made your title a bit shorter). This led the answers to think about words, so they split up the input, did some work to ensure they weren't working on the first character, and then reassembled the result.
But, another way to frame the problem is "How do I remove all the vowels that come after another letter?". The only letter that doesn't come after another letter is the first letter of a word.
The regex for a vowel that comes after another letter is simple (but I'll stick to ASCII here, although it is just as simple for any Unicode letter):
[a-z][aeiou]
That only matches when there is a vowel after the first letter. Now you want to replace all of those with nothing. Use the substitution operator, s///. The /g flag makes all global substitutions and the /i makes it case insensitive:
s/[a-z][aeiou]//gi;
But, there's a problem. It also replaces that leading letter. That's easy enough to fix. The \K in a substitution says to ignore the part of the pattern before it in the replacement. Anything before the \K is not replaced. So, this only replaces the vowels:
s/[a-z]\K[aeiou]//gi;
But, maybe there are vowels next to each other, so throw in the + quantifier for "one or more" of the preceding item:
s/[a-z]\K[aeiou]+//gi;
You don't need to care about words at all.
Some other ways
Saying that a letter must follow another letter has a special zero-width assertion: the non-word boundary, \B (although that also counts digits and underscore as "letters"):
s/\B[aeiou]+//gi;
The \K was introduced v5.10 and was really a nifty trick to have a variable-width lookbehind. But, the lookbehind here is fixed width: it's one character:
s/(?<=[a-z])[aeiou]+//gi;
But, caring about words
Suppose you need to handle each word separately, for some other requirement. It looks like you've mixed a little Python-ish sort of code, and it would be nice if Perl could do that :). The problem doesn't change that much because you can do the same thing for each individual word.
foreach my $word ( split /\s+/, $x ) {
.... # same thing for each word
}
But, here's an interesting twist? How do you put it all back together? The other solutions just use a single space assuming that's the separator. Maybe there should be two spaces, or tabs, or whatever. The split has a special "separator retention mode" that can keep whatever was between the pieces. When you have captures in the split pattern, those capture values are part of the output list:
my #words_and_separators = split /(\s+)/, $x;
Since you know that none of the separators will have vowels, you can make substitutions on them knowing they won't change. This means you can treat them just like the words (that is, there is no special case, which is another thing to think about as you decompose problems). To get your final string with the original spacing, join on the empty string:
my $ending_string = join '', #words_and_separators;
So, here's how that might all look put together. I'll add the /r flag on the substitution so it returns the modified copy instead of working on the original (don't modify the control variable!):
my #words;
foreach my $word ( split /(\s+)/, $x ) {
push #words, $word =~ s/\B[aeiou]+//gr;
}
my $ending_string = join '', #words;
But, that foreach is a bit annoying. This list pipeline is the same, and it's easier to read these bottom to top. Each thing produces a list that flows into the thing above it. This is how I'd probably express it in real code:
my $ending_string =
join '',
map { s/\B[aeiou]+//gr } # each item is in $_
split /(\s+)/, $x;
Now, here's the grand finale. What if we didn't split thing up on whitespace but on whitespace and the first letter of each word? With separator retention mode we know that we only have to affect every other item, so we count them as we do the map:
my $n = 0;
my $ending_string =
join '',
map { ++$n % 2 ? tr/aeiouAEIOU//dr : $_ }
split /((?:^|\s+)[a-z])/i, $x;
But, I wouldn't write this technique in this way because someone would ultimately find me and exact their revenge. Instead, that foreach I found annoying before may soothe the angry masses:
my $n = 0;
foreach ( split /((?:^|\s+)[a-z])/i, $x ) {
print ++$n % 2 ? tr/aeiouAEIOU//dr : $_;
}
This now remembers the actual separators from the original string and leaves alone the first character of the "word" because it's not in the element we will modify.
The code in the foreach doesn't need to use the conditional operator, ?: or some of the other features. The important part is skipping every other element. That split pattern is a bit of a puzzler if you haven't seen it before, but that's what you get with those sorts of requirements. I think modifying a portion of the substring is just as likely to trip up people on a first read.
I mean, if they are going to make you do it the wrong way in the homework, strike back with something that will take up a bit of their time. :)
Oh, this is fun
I had another idea, because tr/// has another task beyond transliteration. It also counts. Because it returns the number of replacements, if you replace anything with itself, you get a count of the occurrences of that thing. You can count vowels, for instance:
my $has_vowels = $string =~ tr/aeiou/aeiou/; # counts vowels
But, with a string of one letter, that means you have a way to tell if it is a vowel:
my $is_vowel = substr( $string, $i, 1 ) =~ tr/aeiou/aeiou/;
You also can know things about the previous character:
my $is_letter = substr( $string, $i - 1, 1 ) =~ tr/a-zA-Z/a-zA-Z/;
Put that together and you can look at any position and know if it's a vowel that follows a letter. If so, you skip that letter. Otherwise, you add that letter to the output:
use v5.10;
$x = "I like apples more than oranges oooooranges\n";
my $output = substr $x, 0, 1; # avoid the -1 trap (end of string!)
for( my $i = 1; $i < length $x; $i++ ) {
if( substr( $x, $i, 1 ) =~ tr/aeiou/aeiou/ ) { # is a vowel
next if substr( $x, $i - 1, 1 ) =~ tr/a-zA-Z/a-zA-Z/;
}
$output .= substr $x, $i, 1;
}
say $output;
This has the fun consequence of using the recommended operator but completely bypassing the intent. But, this is a proper and intended use of tr///.
It appears that you need to put a little more effort into learning Perl before taking on challenges like this. Your example contains a lot of code that simply isn't valid Perl.
$x = "I like apples more than oranges\n"; #the original sentence
foreach $i in #x[1..] {
You assign your text to the scalar variable $x, but then try to use the array variable #x. In Perl, these are two completely separate variables that have no connection whatsoever. Also, in Perl, the range operator (..) needs values at both ends.
If you had an array called #x (and you don't, you have a scalar) then you could do what you're trying to do here with foreach $i (#x)
if $i "AEIOUaeiou";
I'm not sure what you're trying to do here. I guess the nearest useful Perl expression I can see would be something like:
if ($i =~ /^[AEIOUaeiou]$/)
Which would test if $i is a vowel. But that's a regex, so you're not allowed to use it.
Obviously, I'd solve this problem with a regex, but as those are banned, I've reached for some slightly more obscure Perl features in my code below (that's so your teacher won't believe this is your solution if you just cut and paste it):
#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';
my $text = "I like apples more than oranges\n";
# Split the string into an array of words
my #words = split /\s+/, $text;
# For each word...
for (#words) {
# Get a substring that omits the first character
# and use tr/// to remove vowels from that substring
substr($_, 1) =~ tr/AEIOUaeiou//d;
}
# Join the array back together
$text = join ' ', #words;
say $text;
Update: Oh, and notice that I've used tr/AEIUOaeiou//d where you have tr/A E I O U a e i o u//d. It probably won't make any difference here (depending on your approach - but you'll probably be applying it to strings that don't contain spaces) but it's good practice to only include the characters that you want to remove.
We can go over the input string from the end and remove any vowel that's not preceded by a space. We go from right to left so we don't have to adjust the position after each deletion. We don't need to check the very first letter, it shouldn't be ever removed. To remove a vowel, we can use tr///d on the substr of the original string.
for my $i (reverse 1 .. length $x) {
substr($x, $i, 1) =~ tr/aeiouAEIOU//d
if substr($x, $i - 1, 1) ne ' ';
}
Firstly your if statement is wrong.
Secondly this is not a Perl code.
Here is a piece of code that will work, but there is a better way to do it
my $x = "I like apples more than oranges\n";
my $new = "";
my #arr;
foreach my $word (split(' ', $x)) {
#arr = split('', $word);
foreach (my $i; $i<scalar #arr; $i++){
if ($i == 0){
$new .= $arr[$i];
}
elsif (index("AEIOUaeiou", $arr[$i]) == -1) {
$new .= $arr[$i];
}
}
$new .= " ";
}
print "$new\n";
Here I am splitting the string in order to get an array, then I am checking if the given char is a vowel, if it's not, I am appending it to a new string.
Always include
use strict;
use warnings;
on top of your code.
Clearly this is an exercise in lvalues. Obviously. Indubitably!
#!/usr/bin/env perl
# any old perl will do
use 5.010;
use strict;
use warnings;
# This is not idomatic nor fantastic code. Idiotastic?
$_='I am yclept Azure-Orange, queueing to close a query. How are YOU?';
# My little paws typed "local pos" and got
# "Useless localization of match position" :(
# so a busy $b keeps/restores that value
while (/\b./g) {
substr($_,$b=pos,/\b/g && -$b+pos)
# Suggestion to use tr is poetic, not pragmatic,
# ~ tr is sometimes y and y is sometimes a vowel
=~ y/aeiouAEIOU//d;
pos=$b;
}
say
# "say" is the last word.
Was there an embargo against using s/// substitution, or against using all regex? For some reason I thought matching was OK, just not substitution. If matches are OK, I have an idea that "improves" upon this by removing $b through pattern matching side effects. Will see if it pans out. If not, should be pretty easy to replace /\b/ and pos with index and variables, though the definition of word boundary over-simplifies in that case.
(edit) here it is a little more legible with nary a regex
my $text="YO you are the one! The-only-person- asking about double spaces.
Unfortunate about newlines...";
for (my $end=length $text;
$end > 0 && (my $start = rindex $text,' ',$end);
$end = $start-1) {
# y is a beautiful letter, using it for vowels is poetry.
substr($text,2+$start,$end-$start) =~ y/aeiouUOIEA//d;
}
say $text;
Maybe more devious minds will succeed with vec, unpack, open, fork?
You can learn about some of these techniques via
perldoc -f substr
perldoc -f pos
perldoc re
As for my own implementer notes, the least important thing is ending without punctuation so nothing can go after
I want to get the split characters. I tried the below coding, but I can able to get the splitted text only. However if the split characters are same then it should be returned as that single characters
For example if the string is "asa,agas,asa" then only , should be returned.
So in the below case I should get as "| : ;" (joined with space)
use strict;
use warnings;
my $str = "Welcome|a:g;v";
my #value = split /[,;:.%|]/, $str;
foreach my $final (#value) {
print $final, "\n";
}
split splits a string into elements when given what separates those elements, so split is not what you want. Instead, use:
my #punctuations = $str =~ /([,;:.%|])/g;
So you want to get the opposite of split
try:
my #value=split /[^,;:.%|]+/,$str;
It will split on anything but the delimiters you set.
Correction after commnets:
my #value=split /[^,;:.%|]+/,$str;
shift #value;
this works fine, and gives unique answers
#value = ();
foreach(split('',",;:.%|")) { push #value,$_ if $str=~/$_/; }
To extract all the separators only once, you need something more elaborate
my #punctuations = keys %{{ map { $_ => 1 } $str =~ /[,;:.%|]/g }};
Sounds like you call "split characters" what the rest of us call "delimiters" -- if so, the POSIX character class [:punct:] might prove valuable.
OTOH, if you have a defined list of delimiters, and all you want to do is list the ones present in the string, it's much more efficient to use m// rather than split.
How to match different instances of the same word.
Eg: if the string is synergy. How to match it with synergizes, synergism, synergically, synergistic.
I could write the following:
while(<IN>)
{
chomp $_;
my $line= $_;
$word="Synergy";
if($line=~m/$word(\w+)/i)
{
$line=~s/$word/<Effect>$word<\/Effect>/ig;
}
}
What you probably want to do is called stemming.
However, for this to work, you have to stem all the words in the text plus the one you search for. Hopefully all of your listed words result in the same stem. I haven't tested it yet.
use Lingua::Stem;
my $stemmer = Lingua::Stem->new( -locale => 'EN-UK' );
# first convert text to list of words
my #words;
while(<IN>) {
push #words, split(/\b/, $_); # you can do better here
}
# now stem all words.
my $stemmed_words = $stemmer->stem(#words);
# results in an array ref of stems in the same order as the words have been.
# now stem your search
my $stemmed_search = $stemmer->stem($word);
# and do the search from above inside stemmed array.
Now it depends on what you want. If you want to exchange all those words with something, you have to get the indexes of the matched (stemmed) words and do the replacement at the same positions inside your text.
You're going to want to use regular expressions. It is unclear what exactly the criteria you want to match, but in your example all the words start with "synergi" so if($string =~ \bsynergi\w*\b) would find all lines containing "synergi" anywhere in them.
You might want to check out Text::Soundex. For example,
use Text::Soundex;
# The following all return S562
print soundex("synergizes"), "\n";
print soundex("synergism"), "\n";
print soundex("synergically"), "\n";
print soundex("synergistic"), "\n";
Further reading: Perldoc Text::Soundex
I have a log file where some of the entries look like this:
YY/MM/DD HH:MM:SS:MMM <Some constant text> v1=XXX v2=YYY v3=ZZZ v4=AAA AND BBB v5=CCC
and I'm trying to get it into a CSV format:
Date,Time,v1,v2,v3,v4,v5
YY/MM/DD,HH:MM:SS:MMM,XXX,YYY,ZZZ,AAA AND BBB,CCC
I'd like to do this in Perl - speaking personally, I could probably do it far quicker in other languages but I'd really like to expand my horizons a bit.
So far I can get as far as reading the file in and picking out only lines which meet my criteria but I can't seem to get the next stage done. I'll need to splice up the input line but so far I just can't work out how to do this. I've looked at s//and m// but they don't really give me what I want. If anyone can advise me how this can be done or give me pointers I'd much appreciate it.
Important points:
The values in the second part of the line are always in the same order so mapping / re-organising is not necesarily a problem.
Some of the fields have free text which is not quoted :( but as the labels all start v<number>= I'm hoping parsing this should still be a possibility.
Since there is no one delimiter, you'll need to try this a few different ways:
First, split on ' ', then take the first three values:
my #array = split / /, $line;
my ($date, $time, $constant) = splice #array, 0, 3;
Join the rest of the fields together again, and re-split on v\d+= to get the values:
my $rest = join ' ', #array;
# $rest should now be "v1=XXX v2=YYY ..."
my #values = split /\s*v\d+=/, $rest;
shift #values; # since the first element in #values will be empty
print join ',', $date, $time, #values;
Edit: Here's another approach that may be easier to follow, and is slightly more efficient. This takes advantage of the fact that your constant text occurs between the date/time and the value list.
# assume that CONSTANT is your constant text
my ($datetime, $valuelist) = split /\s*CONSTANT\s*/, $line;
my ($date, $time) = split / /, $datetime;
my #values = split /\s*v\d+=/, $valuelist;
shift #values;
print join ',', $date, $time, #values, "\n";
What have you tried with regular expressions and how has it failed? A regex with m// works fine for me:
#!/usr/bin/env perl
use strict;
use warnings;
print "Date,Time,v1,v2,v3,v4,v5\n";
while (my $line = <DATA>) {
my #matched = $line =~ m{^([^ ]+) ([^ ]+).*v1=(.*) v2=(.*) v3=(.*) v4=(.*) v5=(.*)};
print join(',', #matched), "\n";
}
__DATA__
YY/MM/DD HH:MM:SS:MMM <Some constant text> v1=XXX v2=YYY v3=ZZZ v4=AAA AND BBB v5=CCC
Two caveats:
1) v1 cannot contain the substring " v2=", v2 cannot contain " v3=", etc., but, with such a loose format, that's something that would likely cause problems for a human attempting to parse it, too.
2) This code assumes that there will always be v1 through v5. If there are fewer than five v*n* fields, the line will fail to match. If there are more, all additional fields will be appended to v5 (including their v*n* tags).
In case the log is fixed-width, you better off using unpack, you will see its benefits if the log grows very large (performance wise).