http://qs1969.pair.com?node_id=11149891


in reply to Re^2: approximating geological problems with highway data
in thread approximating geological problems with highway data

In sub init_event { ... } 
{
  "name"     => "snowville",
  "date"     => $date_str,
  "time"     => $time_str,
  "location" => { lon => -112.7105234, lat => 41.9655701 },
  42.152429, -112.9842191
},

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Is the 42.152429, -112.9842191 key/value pair from the posted code perhaps a tyop? It's syntactically correct, but looks semantically fishy. Looks like it escaped from the following event record anonymous hash. (Update: OTOH, it looks quite harmless since you're unlikely to ever encounter a "42.152429" key in your code. :)

Also, if init_event() isn't just stub code for the SSCCE, a more succinct way to write it would be 

c:\@Work\Perl\monks>perl

use strict;
use warnings;

use Data::Dump qw(dd);

sub init_event {

    # define unique event records as anonymous hash refs.
    my $ar_events = [
        { "name"     => "Boise",
          "location" => { lon => -116.2, lat => 43.61 },
          },
        { "name"     => "near sublett",
          "location" => { lon => -113.2104084, lat => 42.3278114 },
          },
        { "name"     => "snowville",
          "location" => { lon => -112.7105234, lat => 41.9655701 },
          },
        { "name"     => "juniper",
          "location" => { lon => -112.9842191, lat => 42.152429 },
          },
        # and so on...
        ];

    # add standard date/time to each event record.
    my $date_str = "2021-10-14";
    my $time_str = "03:22:31";

    @{$_}{ qw(date time) } = ($date_str, $time_str) for @$ar_events;

    return $ar_events;

    }

my $ar_ev = init_event();
dd $ar_ev;

^Z
[
  {
    date     => "2021-10-14",
    location => { lat => "43.61", lon => "-116.2" },
    name     => "Boise",
    "time"   => "03:22:31",
  },
  {
    date     => "2021-10-14",
    location => { lat => "42.3278114", lon => "-113.2104084" },
    name     => "near sublett",
    "time"   => "03:22:31",
  },
  {
    date     => "2021-10-14",
    location => { lat => "41.9655701", lon => "-112.7105234" },
    name     => "snowville",
    "time"   => "03:22:31",
  },
  {
    date     => "2021-10-14",
    location => { lat => "42.152429", lon => "-112.9842191" },
    name     => "juniper",
    "time"   => "03:22:31",
  },
]

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Give a man a fish:  <%-{-{-{-<

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Re^4: approximating geological problems with highway data
by Aldebaran (Curate) on Jan 29, 2023 at 06:19 UTC

    Thanks all for helpful source comments. I can now compare numbers from different sources. This link should contain the newest source: 4.am.pl

    Output:

    $ ./4.am.pl
Subroutine get_logger redefined at ./4.am.pl line 146.
INFO: ./4.am.pl
INFO: pi is 3.14159265358979 
INFO: Bonneville max altitude in feet: 5200
INFO:  Boise 43.61  -116.2
INFO: return from the google is 821 meters
INFO: Altitude in feet is 2693.56964
INFO: Difference from max Bonneville elevation is 2506.43036 ft
INFO: USGS elevation is 2697.37 ft
INFO: Percent difference is 0.140990634426756
INFO: distance is 7794.07491881811 miles
INFO: distance is 4656.32531168763 miles
INFO: Percent difference is 50.4039958401085
INFO: ==============
INFO:  near sublett 42.3278114  -113.2104084
INFO: return from the google is 1455 meters
INFO: Altitude in feet is 4773.6222
INFO: Difference from max Bonneville elevation is 426.3778 ft
INFO: USGS elevation is 4780.72 ft
INFO: Percent difference is 0.148577470880213
INFO: distance is 175.16979925839 miles
INFO: distance is 175.486511142723 miles
INFO: Percent difference is 0.180639489402675
INFO: ==============
INFO:  snowville 41.9655701  -112.7105234
INFO: return from the google is 1384 meters
INFO: Altitude in feet is 4540.68256
INFO: Difference from max Bonneville elevation is 659.31744 ft
INFO: USGS elevation is 4545.24 ft
INFO: Percent difference is 0.100318706656456
INFO: distance is 35.8058824322112 miles
INFO: distance is 35.837188345951 miles
INFO: Percent difference is 0.0873941147406608
INFO: ==============
INFO:  juniper 42.152429  -112.9842191
INFO: return from the google is 1577 meters
INFO: Altitude in feet is 5173.88468
INFO: Difference from max Bonneville elevation is 26.1153199999999 ft
INFO: USGS elevation is 5169.2 ft
INFO: Percent difference is 0.0905857419703596
INFO: distance is 19.0729839145012 miles
INFO: distance is 19.0916186594743 miles
INFO: Percent difference is 0.097654599897474
INFO: ==============
$

    [download]

    The first distance is kludged with garbage values, so not too surprised to see 50% error there, but look at how close the values tended to be! I think I might have 3 sig figs. The modified script is approximately:

    
### Elevation with USGS

  use Geo::WebService::Elevation::USGS;

  my $eq = Geo::WebService::Elevation::USGS->new();
  my $alt =
    $eq->elevation( $event->{location}->{lat}, $event->{location}->{lo
+n} )
    ->{Elevation};

  $logger->info("USGS elevation is $alt ft");

### compare values

  my $percent = percent_error( $feet, $alt );
  $logger->info("Percent difference is $percent");

### home cooked distance
  my $d = distance(
    $prev_lat, $prev_long,
    $event->{location}->{lat},
    $event->{location}->{lon}, "M"
  );
  $logger->info("distance is $d miles");


### distance with GPS::Point
  use GPS::Point;
  my $gps = GPS::Point->new( lat => $prev_lat, lon => $prev_long );
  my $dist =
    $gps->distance( $event->{location}->{lat}, $event->{location}->{lo
+n} );
  my $feet2 = 3.28084 * $dist;
  my $miles = $feet2 / 5280;

  #$logger->info("distance is $feet2 feet");
  $logger->info("distance is $miles miles");
 

### compare values

  my $percent2 = percent_error( $d, $miles );
  $logger->info("Percent difference is $percent2");

    [download]

    Really happy to work up a different source for elevations, and look, I ran into Tom Wyant's software again:

    Running Build test for WYANT/Geo-WebService-Elevation-USGS-0.120.tar.g
+z
t/basic.t .. ok    
t/elev.t ... # Accessing https://nationalmap.gov/epqs/pqs.php

    [download]

    Cheers,

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