in reply to Re^2: Setting flags in a conditional
in thread Setting flags in a conditional

I thought maybe it was the location of the $in_port flag initialization - it should not be in the loop. But it's still not skipping the line nor is it setting the flag. I must have a test/condition problem. I'll look there. I'm pretty sure the code should look like this: 

my $in_port;
$in_port = "false";
   foreach my $ts ($te->tables) {
   foreach my $row ($ts->rows) {
   if ($row ne "Ships in port or not reporting today:") # not a ship n
+ame; skip this and set the in_port flag for all remaining ships
      {
      $out_fh->print (join(',', @$row), ",", $in_port, "\n");
      }
      else {$in_port = "true"};
   }
 }

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Re^4: Setting flags in a conditional
by BrowserUk (Patriarch) on Mar 20, 2008 at 06:44 UTC

    Contrast if ($row ne "Ships in ... with join(',', @$row)?

    In the second example you are using $row as an array reference. In the first, as a string. To paraphrase someone, you can't just make it up and expect things to work :)

    Try printing $row and @$row inside the second loop. It may give you a clue as to what you should be looking at to detect the condition. I suspect that you should be doing something along the lines of: 

    foreach my $row ($ts->rows) {
   if ($row->[ 3 ] ne "Ships in port or not reporting today:") {
   ...

    [download]

    But if you print the records to the screen, print join',', @$row; then you'll be able to see which element of $row contains the text you are looking for. (Remember arrays start counting from 0.)

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
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      BrowserUK, that's a good tip. Upon looking at the results, it occurs to me that no ships have a ':' in their name. But it's not clear to me how to parse for a colon whilst in the loop. As you say, @$row is an array; but I won't know what the element number is going to be from run to run.

      Can I do it this way at all?

[reply]
        As you say, @$row is an array; but I won't know what the element number is going to be from run to run.

        You have a pretty deep misunderstanding of the code you are using. $table->rows() returns a list of arrays. Ie. $row is an array reference representing the fields (or columns) of each row of the table.

        So whilst the position (row number) of the row containing the text Ships in port or not reporting today: will vary from run to run. The field or column within that row that contains the text will not.

        I used the following code to dump all the tables from the url you posted in another thread to the screen, with '|' between each element of the rows: 

        #! perl -slw
use strict;
use LWP::Simple;
use HTML::TableExtract;

my $te = new HTML::TableExtract;
$te->parse( get( 'http://www.sailwx.info/shiptrack/cruiseships.phtml' 
+) );

for my $table ( $te->tables ) {
    print "\n-----------\n";
    for my $row ( $table->rows ) {
        local $^W;
        print join '|', @$row;
    }
}

        [download]

        Redirecting the output of that, junk | more, I got: 

        ...
-----------

Ship|last reported (UTC)|position|Callsign
BATFR20|2008-Mar-20 2100|N 43░00', E 005░36'|BATFR20
BATFR21|2008-Mar-20 2100|N 41░36', E 008░24'|BATFR21
BATFR22|2008-Mar-20 2100|N 42░54', E 005░54'|BATFR22
...
Carribean Princess|2008-Mar-19 0600|N 19░18', W 065░18'|ZC
+DG8
Prinsendam|2008-Mar-19 0300|N 27░24', W 040░24'|PBGH
Ships in port or not reporting today:|||
TUSTUMENA|2008-Mar-18 1700|N 60░48', W 147░12'|WNGW
Oosterdam|2008-Mar-18 0800|N 23░00', W 107░48'|PBKH
...

        [download]

        From the empty fields on the end of Ships in port or not reporting today:|||, I can tell that the text that marks the transition from those ships at sea, to those in port, is returned in $row->[ 0 ].

        So your test becomes: 

        ...
for my $row ( $table->rows ) {
    if( $row->[ 0 ] ne 'Ships in port or not reporting today:' ) {
    ...

        [download]
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
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