in reply to Re^2: Addional "year" matching functionality in word matching script
in thread Addional "year" matching functionality in word matching script

Yes, I chose $year_left as the name for the variable holding the year number on the left side of the comparison, and $year_right for the right side of the comparison.

You can look at a string and guess if it contains a four digit year by using the following code for example:

my $str = 'this is some text 1989 blah';
my $year;
$year = $1
    if( $str =~ /\b((?:19|20)\d\d)\b/ );

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The regular expression looks at whether the string contains at least one number with four digits that starts with 19 or 20, and sets $year to the first such number. You could put that code into a subroutine as follows to allow for easy reuse:

sub find_year {
    my( $str ) = @_;
    my $year;
    $year = $1
        if( $str =~ /\b((?:19|20)\d\d)\b/ );
    return $year
}

[download]

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Re^4: Addional "year" matching functionality in word matching script
by bms9nmh (Novice) on Jun 27, 2016 at 16:13 UTC
    Ok, I've been trying to break things down with the info you have provided, intially with a simpler problem so I can work out whats going on. I'm trying to print the year from the title in a file called csv3 (which contains 1989 in the title) using the following code but it isn't printing anything, what am I doing wrong? 
     #!/bin/perl

open CSV3, "<csv3" or die;

while (<CSV3>) {

  chomp;

my ($title) = $_ =~ /^.+?,\s*([^,]+?),/; #/ match the title         

    my %words;

    $words{$_}++ for split /\s+/, $title;    #/ get words             

    ## Collect unique words                                           
    #+                                             
    #    my @titlewords = keys(%words);                               
+           
my @titlewords = keys(%words);
#print "$title"


}



sub find_year {
    my( $str ) = @_;
    my $year;
    $year = $1
        if( $str =~ /\b((?:19|20)\d\d)\b/ );
    return $year
}

&find_year ($title);

    [download]
    I would have thought the   &find_year ($title); would have taken the title and applied the subroutine to this string, picking out the 1989?
[reply]
[d/l]
[select]

      You call find_year(), but you never print its output. For testing, you could start with:

      for my $title (
    "Let's party like it's 1999",
    "If 6 was 9",
    "If 6 was 9",
    "Summer of 69",
    "Disco 2000",
) {
    print $title , " => ", find_year($title), "\n";
}

      [download]
[reply]
[d/l]
[select]
        I can see this print each line in the title and the  => bit shows the year being extracted (not sure that's the right word) from the title. 
        sub find_year {
    my( $str ) = @_;
    my $year;
    $year = $1
        if( $str =~ /\b((?:19|20)\d\d)\b/ );
    return $year
}


for my $title (
    "Let's party like it's 1999",
    "If 6 was 9",
    "If 6 was 9",
    "Summer of 69",
    "Disco 2000",
) {
    print $title , " => ", find_year($title), "\n";
}

        [download]
        One thing I'm not sure of is, I've tried to integrate the info above so that I can use the $title from a csv file rather than titles typed into the script (as in the above example). I have attempted this below but it's not working. I'd appreciate if someone could tell me what exactly i'm doing wrong. I know I'm being prompted to learn which I'm happy to do, but I think I would learn faster if someone told me what I have done wrong in the piece of code below. 
        sub find_year {
    my( $str ) = @_;
    my $year;
    $year = $1
        if( $str =~ /\b((?:19|20)\d\d)\b/ );
    return $year
}

#get the title from csv3

open CSV3, "<csv3" or die;

while (<CSV3>) {

  chomp;

  my ($title) = $_ =~ /^.+?,\s*([^,]+?),/; #/ match the title
}

for my $title {
print $title , " => ", find_year($title), "\n"; }

        [download]
[reply]
[d/l]
[select]
      The code as posted doesn't contain an (uncommented) print or other output statement - so, what should it print?
[reply]
[d/l]

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