1. One of the Atlanta.pm members was raving at the last meeting about how useful Mojo is for web munging (scraping, parsing, and re-publishing as an internal "API"). I have no personal experience with Mojo, but I trust his ravings.

Then Mojo it is. Thanks so much for your post, Util, it helped me get farther in a lot of ways. I was able to get this to work on the command line, but I couldn't get Corion's curl converter to recognize a -S option, nor could I see it from man curl. The command seems to give the same output without it:

$ curl -s 'https://nationalmap.gov/epqs/pqs.php?units=Meters&output=js
+on&x=-83.65&y=41.37' | jq '.USGS_Elevation_Point_Query_Service.Elevat
+ion_Query.Elevation'
212.77
$

[download]

Unfortunately, I couldn't get this value in the perl script which I'm posting below. (Partial credit is great for me.)

NOAA has the elevation of the 2.5km grid polygon, which will be lower granularity, but might (I'm just guessing) be helpful for water, where the elevation varies:

I was thrilled to see this solution at the same server where I had been fishing! Furthermore, your example along with the jq command to see where the good data is in the haystack was exactly what I needed to get some numbers out of this. First I'll post the log then the source.

2020/06/23 15:26:07 INFO ./5.2.elev.pl 
2020/06/23 15:26:07 INFO {
  "USGS_Elevation_Point_Query_Service" => {
    "Elevation_Query" => {
      "Data_Source" => "3DEP 1/3 arc-second",
      "Elevation" => -1000000,
      "Units" => "Meters",
      "x" => "41.37",
      "y" => "-83.65"
    }
  }
}
 
2020/06/23 15:26:07 INFO 41.37 -83.65 0.208 
2020/06/23 15:26:07 INFO ============== 
2020/06/23 15:26:07 INFO https://api.weather.gov/points/41.37,-83.65 
2020/06/23 15:26:08 INFO CLE 
2020/06/23 15:26:08 INFO 16  52 
2020/06/23 15:26:08 INFO ============== 
2020/06/23 15:26:08 INFO https://api.weather.gov/gridpoints/CLE/16,52 
2020/06/23 15:26:08 INFO ============== 
2020/06/23 15:26:08 INFO 213.0552 wmoUnit:m

[download]

Source:

#!/usr/bin/env perl

use strict;
use warnings;
use 5.016;
use Log::Log4perl;
use Mojo::UserAgent;
use open ':std', OUT => ':utf8';
use Mojo::Util qw(dumper);

# get rid of old log
my $file = '/home/hogan/Documents/hogan/logs/4.log4perl.txt';
unlink $file or warn "Could not unlink $file: $!";
my $log_conf4 = "/home/hogan/Documents/hogan/logs/conf_files/4.conf";
Log::Log4perl::init($log_conf4);    #info
my $logger = Log::Log4perl->get_logger();
$logger->info("$0");

# weston, OH 41.37,-83.65
my $lat  = 41.37;
my $long = -83.65;

# the API docs says you must identify yourself, please make this somet
+hing legit
my $name = '(example.com, contact@example.com)';

my $url2 =
"https://nationalmap.gov/epqs/pqs.php?output=json&units=Meters&x=$lat&
+y=$long";
my $ub = Mojo::UserAgent->new;
$ub->transactor->name($name);

# get JSON response
my $qv = $ub->get($url2)->res->json;
$logger->info( dumper $qv);

my $elev = .208;    # 676 ft = .206 +.02 for observer  #km
$logger->info("$lat $long $elev");

my $url1 = "https://api.weather.gov/points/$lat,$long";
$logger->info("==============");
$logger->info($url1);

my $ua = Mojo::UserAgent->new;
$ua->transactor->name($name);

# get JSON response
my $pv      = $ua->get($url1)->res->json->{properties};
my $station = $pv->{'cwa'};
my $gridX   = $pv->{'gridX'};
my $gridY   = $pv->{'gridY'};
$logger->info("$station");
$logger->info("$gridX  $gridY");

$logger->info("==============");

## new transaction
## find elevation 

my $uc = Mojo::UserAgent->new;
$uc->transactor->name($name);
my $url3 = "https://api.weather.gov/gridpoints/$station/$gridX,$gridY"
+;
$logger->info( $url3 );
my $json = $uc->get($url3)->res->json;
#my $props = $json->{properties};
my $elev2 = $json->{properties}->{elevation}->{value};
my $unit = $json->{properties}->{elevation}->{unitCode};
$logger->info("==============");
#$logger->info(dumper($props));
$logger->info( $elev2 . ' '. $unit);

__END__

[download]

It takes me time fiddling with these things with perl and jq in order to get my head around them.

Q1) How do I get a valid value for the usgs query in lexical perl?

Thanks again for your post,

In reply to Re^2: creating a webpage to fetch/calculate weather data by Aldebaran
in thread creating a webpage to fetch/calculate weather data by Aldebaran

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.