getting numeric data from a file into an array

[jmccaslin]

I have a simple file in the format

TIME
number of steps:          13
time values:  2.83506E+03  2.83697E+03  2.83911E+03
 2.84117E+03  2.84331E+03  2.84544E+03
 2.84750E+03  2.84958E+03  2.85172E+03
 2.85383E+03  2.85588E+03  2.85804E+03
 2.86012E+03

and I would like to take the time values and store them in an array. I'm sure this is very simple, but I'm not sure how to do it using Perl... Any help is much appreciated.

[runrig]

...I'm not sure how to do it

What have you tried so far? Just so you know, we're usually happy to help, but this is not a code writing service or a place to get homework answers.

And welcome to PerlMonks!

[jmccaslin]

I should have been more specific. I was suspicious that matching reg exp would do the trick. Here is what I have so far:

# read in times
open MYFILE, "<$dir/structs/times";
my @temptimes = <MYFILE>;
close(MYFILE);
print "$#temptimes\n";
my @strtimes;
for (my $i = 2;$i <= $#temptimes;$i++){
  if ($temptimes[$i] =~ m/(\d+.\d+)/){
    print "$1\n";
  }
}

I'm having trouble reading the other two values and storing them in an array. I figured I could just multiply by 10^3 to account for the "E+03", as I didn't know how to deal with the "+" sign. Sorry if it seemed like I'm looking for homework solutions - in fact this is not homework. I can do this in other languages, I just want to learn Perl.

[roboticus]

jmccaslin:

Here's a quickie example:

use strict;
use warnings;

while (my $line = <DATA>) {
    chomp;
    print "INPUT LINE: $line\n";

    # Read all the times from the line and place into array
    my @times = ($line=~m/[-+0-9.E]+/g);

    # Print the values
    print $_*1000, "\n" for @times;
}

__DATA__
  2.83506E+03  2.83697E+03  2.83911E+03
  2.84117E+03  2.84331E+03  2.84544E+03
  2.84750E+03  2.84958E+03  2.85172E+03
  2.85383E+03  2.85588E+03  2.85804E+03
  2.86012E+03

This gives me:

$ perl foo.pl
Use of uninitialized value $_ in scalar chomp at foo.pl line 5, <DATA>
+ line 1.
INPUT LINE:   2.83506E+03  2.83697E+03  2.83911E+03

2835060
2836970
2839110
Use of uninitialized value $_ in scalar chomp at foo.pl line 5, <DATA>
+ line 2.
INPUT LINE:   2.84117E+03  2.84331E+03  2.84544E+03

2841170
2843310
2845440
Use of uninitialized value $_ in scalar chomp at foo.pl line 5, <DATA>
+ line 3.
INPUT LINE:   2.84750E+03  2.84958E+03  2.85172E+03

2847500
2849580
2851720
Use of uninitialized value $_ in scalar chomp at foo.pl line 5, <DATA>
+ line 4.
INPUT LINE:   2.85383E+03  2.85588E+03  2.85804E+03

2853830
2855880
2858040
Use of uninitialized value $_ in scalar chomp at foo.pl line 5, <DATA>
+ line 5.
INPUT LINE:   2.86012E+03

2860120

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[jmccaslin]

Thanks for the response, that seems to do what I need.

[NetWallah]

Here is a more "perlish" Warning-free way: (Deliberately avoiding regular expressions)

use strict;
use warnings;

my @values;
my $special_string_found = 0;
my $special_string = 'time values:';

while (defined( my $line= <DATA>)) {
   if (not $special_string_found ){
      next unless  $special_string eq substr($line,0,length($special_s
+tring));
      $special_string_found = 1;
      $line = substr($line,length($special_string)+1);
   }
   push @values, split(' ' ,$line);
}

print qq|$_\n| for @values;
__DATA__
TIME
number of steps:          13
time values:  2.83506E+03  2.83697E+03  2.83911E+03
 2.84117E+03  2.84331E+03  2.84544E+03
 2.84750E+03  2.84958E+03  2.85172E+03
 2.85383E+03  2.85588E+03  2.85804E+03
 2.86012E+03

[jmccaslin]

I appreciate seeing the warning-free solution, and I must admit it's a little comforting to see it done without reg exp.