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</pre><pre class="rust"><code><span class="kw">use</span> <span class="ident">std::fmt</span>;
<span class="kw">use</span> <span class="ident">std::io</span>::{<span class="ident">BufRead</span>, <span class="ident">BufReader</span>, <span class="ident">Write</span>};

<span class="kw">use</span> <span class="ident">anyhow::Result</span>;
<span class="kw">use</span> <span class="ident">fs_err::File</span>;
<span class="kw">use</span> <span class="ident">geojson</span>::{<span class="ident">GeoJson</span>, <span class="ident">Value</span>};
<span class="kw">use</span> <span class="ident">ordered_float::NotNan</span>;
<span class="kw">use</span> <span class="ident">serde</span>::{<span class="ident">Deserialize</span>, <span class="ident">Serialize</span>};

<span class="kw">use</span> <span class="kw">crate</span>::{<span class="ident">Distance</span>, <span class="ident">GPSBounds</span>, <span class="ident">Pt2D</span>};

<span class="doccomment">/// Represents a (longitude, latitude) point.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">PartialOrd</span>, <span class="ident">Ord</span>, <span class="ident">Debug</span>, <span class="ident">Serialize</span>, <span class="ident">Deserialize</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">LonLat</span> {
    <span class="ident">longitude</span>: <span class="ident">NotNan</span><span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span>,
    <span class="ident">latitude</span>: <span class="ident">NotNan</span><span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span>,
}

<span class="kw">impl</span> <span class="ident">LonLat</span> {
    <span class="doccomment">/// Note the order of arguments!</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">lon</span>: <span class="ident">f64</span>, <span class="ident">lat</span>: <span class="ident">f64</span>) -&gt; <span class="ident">LonLat</span> {
        <span class="ident">LonLat</span> {
            <span class="ident">longitude</span>: <span class="ident">NotNan::new</span>(<span class="ident">lon</span>).<span class="ident">unwrap</span>(),
            <span class="ident">latitude</span>: <span class="ident">NotNan::new</span>(<span class="ident">lat</span>).<span class="ident">unwrap</span>(),
        }
    }

    <span class="doccomment">/// Returns the longitude of this point.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">x</span>(<span class="self">self</span>) -&gt; <span class="ident">f64</span> {
        <span class="self">self</span>.<span class="ident">longitude</span>.<span class="ident">into_inner</span>()
    }

    <span class="doccomment">/// Returns the latitude of this point.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">y</span>(<span class="self">self</span>) -&gt; <span class="ident">f64</span> {
        <span class="self">self</span>.<span class="ident">latitude</span>.<span class="ident">into_inner</span>()
    }

    <span class="doccomment">/// Transform this to a world-space point. Can go out of bounds.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">to_pt</span>(<span class="self">self</span>, <span class="ident">b</span>: <span class="kw-2">&amp;</span><span class="ident">GPSBounds</span>) -&gt; <span class="ident">Pt2D</span> {
        <span class="kw">let</span> (<span class="ident">width</span>, <span class="ident">height</span>) <span class="op">=</span> {
            <span class="kw">let</span> <span class="ident">pt</span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">get_max_world_pt</span>();
            (<span class="ident">pt</span>.<span class="ident">x</span>(), <span class="ident">pt</span>.<span class="ident">y</span>())
        };

        <span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> (<span class="self">self</span>.<span class="ident">x</span>() <span class="op">-</span> <span class="ident">b</span>.<span class="ident">min_lon</span>) <span class="op">/</span> (<span class="ident">b</span>.<span class="ident">max_lon</span> <span class="op">-</span> <span class="ident">b</span>.<span class="ident">min_lon</span>) <span class="op">*</span> <span class="ident">width</span>;
        <span class="comment">// Invert y, so that the northernmost latitude is 0. Screen drawing order, not Cartesian</span>
        <span class="comment">// grid.</span>
        <span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">height</span> <span class="op">-</span> ((<span class="self">self</span>.<span class="ident">y</span>() <span class="op">-</span> <span class="ident">b</span>.<span class="ident">min_lat</span>) <span class="op">/</span> (<span class="ident">b</span>.<span class="ident">max_lat</span> <span class="op">-</span> <span class="ident">b</span>.<span class="ident">min_lat</span>) <span class="op">*</span> <span class="ident">height</span>);
        <span class="ident">Pt2D::new</span>(<span class="ident">x</span>, <span class="ident">y</span>)
    }

    <span class="doccomment">/// Returns the Haversine distance to another point.</span>
    <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">gps_dist</span>(<span class="self">self</span>, <span class="ident">other</span>: <span class="ident">LonLat</span>) -&gt; <span class="ident">Distance</span> {
        <span class="kw">let</span> <span class="ident">earth_radius_m</span> <span class="op">=</span> <span class="number">6_371_000.0</span>;
        <span class="kw">let</span> <span class="ident">lon1</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">x</span>().<span class="ident">to_radians</span>();
        <span class="kw">let</span> <span class="ident">lon2</span> <span class="op">=</span> <span class="ident">other</span>.<span class="ident">x</span>().<span class="ident">to_radians</span>();
        <span class="kw">let</span> <span class="ident">lat1</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">y</span>().<span class="ident">to_radians</span>();
        <span class="kw">let</span> <span class="ident">lat2</span> <span class="op">=</span> <span class="ident">other</span>.<span class="ident">y</span>().<span class="ident">to_radians</span>();

        <span class="kw">let</span> <span class="ident">delta_lat</span> <span class="op">=</span> <span class="ident">lat2</span> <span class="op">-</span> <span class="ident">lat1</span>;
        <span class="kw">let</span> <span class="ident">delta_lon</span> <span class="op">=</span> <span class="ident">lon2</span> <span class="op">-</span> <span class="ident">lon1</span>;

        <span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> (<span class="ident">delta_lat</span> <span class="op">/</span> <span class="number">2.0</span>).<span class="ident">sin</span>().<span class="ident">powi</span>(<span class="number">2</span>)
            <span class="op">+</span> (<span class="ident">delta_lon</span> <span class="op">/</span> <span class="number">2.0</span>).<span class="ident">sin</span>().<span class="ident">powi</span>(<span class="number">2</span>) <span class="op">*</span> <span class="ident">lat1</span>.<span class="ident">cos</span>() <span class="op">*</span> <span class="ident">lat2</span>.<span class="ident">cos</span>();
        <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="number">2.0</span> <span class="op">*</span> <span class="ident">a</span>.<span class="ident">sqrt</span>().<span class="ident">atan2</span>((<span class="number">1.0</span> <span class="op">-</span> <span class="ident">a</span>).<span class="ident">sqrt</span>());
        <span class="ident">Distance::meters</span>(<span class="ident">earth_radius_m</span> <span class="op">*</span> <span class="ident">c</span>)
    }

    <span class="doccomment">/// Pretty meaningless units, for comparing distances very roughly</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">fast_dist</span>(<span class="self">self</span>, <span class="ident">other</span>: <span class="ident">LonLat</span>) -&gt; <span class="ident">NotNan</span><span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span> {
        <span class="ident">NotNan::new</span>((<span class="self">self</span>.<span class="ident">x</span>() <span class="op">-</span> <span class="ident">other</span>.<span class="ident">x</span>()).<span class="ident">powi</span>(<span class="number">2</span>) <span class="op">+</span> (<span class="self">self</span>.<span class="ident">y</span>() <span class="op">-</span> <span class="ident">other</span>.<span class="ident">y</span>()).<span class="ident">powi</span>(<span class="number">2</span>)).<span class="ident">unwrap</span>()
    }

    <span class="doccomment">/// Parses a file in the https://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format</span>
    <span class="doccomment">/// and returns all points.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">read_osmosis_polygon</span>(<span class="ident">path</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">LonLat</span><span class="op">&gt;</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="ident">f</span> <span class="op">=</span> <span class="ident">File::open</span>(<span class="ident">path</span>)<span class="question-mark">?</span>;
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pts</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> (<span class="ident">idx</span>, <span class="ident">line</span>) <span class="kw">in</span> <span class="ident">BufReader::new</span>(<span class="ident">f</span>).<span class="ident">lines</span>().<span class="ident">enumerate</span>() {
            <span class="kw">if</span> <span class="ident">idx</span> <span class="op">&lt;</span> <span class="number">2</span> {
                <span class="kw">continue</span>;
            }
            <span class="kw">let</span> <span class="ident">line</span> <span class="op">=</span> <span class="ident">line</span><span class="question-mark">?</span>;
            <span class="kw">if</span> <span class="ident">line</span> <span class="op">==</span> <span class="string">&quot;END&quot;</span> {
                <span class="kw">break</span>;
            }
            <span class="kw">let</span> <span class="ident">parts</span> <span class="op">=</span> <span class="ident">line</span>.<span class="ident">trim</span>().<span class="ident">split</span>(<span class="string">&quot;    &quot;</span>).<span class="ident">collect</span>::<span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="kw">_</span><span class="op">&gt;</span><span class="op">&gt;</span>();
            <span class="ident">pts</span>.<span class="ident">push</span>(<span class="ident">LonLat::new</span>(
                <span class="ident">parts</span>[<span class="number">0</span>].<span class="ident">parse</span>::<span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span>()<span class="question-mark">?</span>,
                <span class="ident">parts</span>[<span class="number">1</span>].<span class="ident">parse</span>::<span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span>()<span class="question-mark">?</span>,
            ));
        }
        <span class="prelude-val">Ok</span>(<span class="ident">pts</span>)
    }

    <span class="doccomment">/// Writes a set of points to a file in the</span>
    <span class="doccomment">/// https://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format. The input should</span>
    <span class="doccomment">/// be a closed ring, with the first and last point matching.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">write_osmosis_polygon</span>(<span class="ident">path</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">pts</span>: <span class="kw-2">&amp;</span>[<span class="ident">LonLat</span>]) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span>()<span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">f</span> <span class="op">=</span> <span class="ident">File::create</span>(<span class="ident">path</span>)<span class="question-mark">?</span>;
        <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;boundary&quot;</span>)<span class="question-mark">?</span>;
        <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;1&quot;</span>)<span class="question-mark">?</span>;
        <span class="kw">for</span> <span class="ident">pt</span> <span class="kw">in</span> <span class="ident">pts</span> {
            <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;     {}    {}&quot;</span>, <span class="ident">pt</span>.<span class="ident">x</span>(), <span class="ident">pt</span>.<span class="ident">y</span>())<span class="question-mark">?</span>;
        }
        <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;END&quot;</span>)<span class="question-mark">?</span>;
        <span class="macro">writeln!</span>(<span class="ident">f</span>, <span class="string">&quot;END&quot;</span>)<span class="question-mark">?</span>;
        <span class="prelude-val">Ok</span>(())
    }

    <span class="doccomment">/// Finds the average of a set of coordinates.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">center</span>(<span class="ident">pts</span>: <span class="kw-2">&amp;</span>[<span class="ident">LonLat</span>]) -&gt; <span class="ident">LonLat</span> {
        <span class="kw">if</span> <span class="ident">pts</span>.<span class="ident">is_empty</span>() {
            <span class="macro">panic!</span>(<span class="string">&quot;Can&#39;t find center of 0 points&quot;</span>);
        }
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">0.0</span>;
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">y</span> <span class="op">=</span> <span class="number">0.0</span>;
        <span class="kw">for</span> <span class="ident">pt</span> <span class="kw">in</span> <span class="ident">pts</span> {
            <span class="ident">x</span> <span class="op">+</span><span class="op">=</span> <span class="ident">pt</span>.<span class="ident">x</span>();
            <span class="ident">y</span> <span class="op">+</span><span class="op">=</span> <span class="ident">pt</span>.<span class="ident">y</span>();
        }
        <span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="ident">pts</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">f64</span>;
        <span class="ident">LonLat::new</span>(<span class="ident">x</span> <span class="op">/</span> <span class="ident">len</span>, <span class="ident">y</span> <span class="op">/</span> <span class="ident">len</span>)
    }

    <span class="doccomment">/// Parses a WKT-style line-string into a list of coordinates.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">parse_wkt_linestring</span>(<span class="ident">raw</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>) -&gt; <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">LonLat</span><span class="op">&gt;</span><span class="op">&gt;</span> {
        <span class="comment">// Input is something like LINESTRING (-111.9263026 33.4245036, -111.9275146 33.4245016,</span>
        <span class="comment">// -111.9278751 33.4233106)</span>
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pts</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="comment">// -111.9446 33.425474, -111.9442814 33.4254737, -111.9442762 33.426894</span>
        <span class="kw">for</span> <span class="ident">pair</span> <span class="kw">in</span> <span class="ident">raw</span>
            .<span class="ident">strip_prefix</span>(<span class="string">&quot;LINESTRING (&quot;</span>)<span class="question-mark">?</span>
            .<span class="ident">strip_suffix</span>(<span class="string">&#39;)&#39;</span>)<span class="question-mark">?</span>
            .<span class="ident">split</span>(<span class="string">&quot;, &quot;</span>)
        {
            <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">nums</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
            <span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">pair</span>.<span class="ident">split</span>(<span class="string">&#39; &#39;</span>) {
                <span class="ident">nums</span>.<span class="ident">push</span>(<span class="ident">x</span>.<span class="ident">parse</span>::<span class="op">&lt;</span><span class="ident">f64</span><span class="op">&gt;</span>().<span class="ident">ok</span>()<span class="question-mark">?</span>);
            }
            <span class="kw">if</span> <span class="ident">nums</span>.<span class="ident">len</span>() <span class="op">!</span><span class="op">=</span> <span class="number">2</span> {
                <span class="kw">return</span> <span class="prelude-val">None</span>;
            }
            <span class="ident">pts</span>.<span class="ident">push</span>(<span class="ident">LonLat::new</span>(<span class="ident">nums</span>[<span class="number">0</span>], <span class="ident">nums</span>[<span class="number">1</span>]));
        }
        <span class="kw">if</span> <span class="ident">pts</span>.<span class="ident">len</span>() <span class="op">&lt;</span> <span class="number">2</span> {
            <span class="kw">return</span> <span class="prelude-val">None</span>;
        }
        <span class="prelude-val">Some</span>(<span class="ident">pts</span>)
    }

    <span class="doccomment">/// Extract polygons from a raw GeoJSON string. For multipolygons, only returns the first</span>
    <span class="doccomment">/// member. If the GeoJSON feature has a property called `name`, this will also be returned.</span>
    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">parse_geojson_polygons</span>(<span class="ident">raw</span>: <span class="ident">String</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span>(<span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">LonLat</span><span class="op">&gt;</span>, <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">String</span><span class="op">&gt;</span>)<span class="op">&gt;</span><span class="op">&gt;</span> {
        <span class="kw">let</span> <span class="ident">geojson</span> <span class="op">=</span> <span class="ident">raw</span>.<span class="ident">parse</span>::<span class="op">&lt;</span><span class="ident">GeoJson</span><span class="op">&gt;</span>()<span class="question-mark">?</span>;
        <span class="kw">let</span> <span class="ident">features</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">geojson</span> {
            <span class="ident">GeoJson::Feature</span>(<span class="ident">feature</span>) =&gt; <span class="macro">vec!</span>[<span class="ident">feature</span>],
            <span class="ident">GeoJson::FeatureCollection</span>(<span class="ident">feature_collection</span>) =&gt; <span class="ident">feature_collection</span>.<span class="ident">features</span>,
            <span class="kw">_</span> =&gt; <span class="macro">anyhow::bail!</span>(<span class="string">&quot;Unexpected geojson: {:?}&quot;</span>, <span class="ident">geojson</span>),
        };
        <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">polygons</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
        <span class="kw">for</span> <span class="kw-2">mut</span> <span class="ident">feature</span> <span class="kw">in</span> <span class="ident">features</span> {
            <span class="kw">let</span> <span class="ident">points</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">feature</span>.<span class="ident">geometry</span>.<span class="ident">take</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">g</span><span class="op">|</span> <span class="ident">g</span>.<span class="ident">value</span>) {
                <span class="prelude-val">Some</span>(<span class="ident">Value::MultiPolygon</span>(<span class="ident">multi_polygon</span>)) =&gt; <span class="ident">multi_polygon</span>[<span class="number">0</span>][<span class="number">0</span>].<span class="ident">clone</span>(),
                <span class="prelude-val">Some</span>(<span class="ident">Value::Polygon</span>(<span class="ident">polygon</span>)) =&gt; <span class="ident">polygon</span>[<span class="number">0</span>].<span class="ident">clone</span>(),
                <span class="kw">_</span> =&gt; {
                    <span class="macro">anyhow::bail!</span>(<span class="string">&quot;Unexpected feature: {:?}&quot;</span>, <span class="ident">feature</span>);
                }
            };
            <span class="kw">let</span> <span class="ident">name</span> <span class="op">=</span> <span class="ident">feature</span>
                .<span class="ident">property</span>(<span class="string">&quot;name&quot;</span>)
                .<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">value</span><span class="op">|</span> <span class="ident">value</span>.<span class="ident">as_str</span>())
                .<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">to_string</span>());
            <span class="ident">polygons</span>.<span class="ident">push</span>((
                <span class="ident">points</span>
                    .<span class="ident">into_iter</span>()
                    .<span class="ident">map</span>(<span class="op">|</span><span class="ident">pt</span><span class="op">|</span> <span class="ident">LonLat::new</span>(<span class="ident">pt</span>[<span class="number">0</span>], <span class="ident">pt</span>[<span class="number">1</span>]))
                    .<span class="ident">collect</span>(),
                <span class="ident">name</span>,
            ));
        }
        <span class="prelude-val">Ok</span>(<span class="ident">polygons</span>)
    }

    <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">to_geojson</span>(<span class="self">self</span>) -&gt; <span class="ident">geojson::Geometry</span> {
        <span class="ident">geojson::Geometry::new</span>(<span class="ident">geojson::Value::Point</span>(<span class="macro">vec!</span>[<span class="self">self</span>.<span class="ident">x</span>(), <span class="self">self</span>.<span class="ident">y</span>()]))
    }
}

<span class="kw">impl</span> <span class="ident">fmt::Display</span> <span class="kw">for</span> <span class="ident">LonLat</span> {
    <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&amp;mut</span> <span class="ident">fmt::Formatter</span>) -&gt; <span class="ident">fmt::Result</span> {
        <span class="macro">write!</span>(<span class="ident">f</span>, <span class="string">&quot;LonLat({0}, {1})&quot;</span>, <span class="self">self</span>.<span class="ident">x</span>(), <span class="self">self</span>.<span class="ident">y</span>())
    }
}

<span class="kw">impl</span> <span class="ident">From</span><span class="op">&lt;</span><span class="ident">LonLat</span><span class="op">&gt;</span> <span class="kw">for</span> <span class="ident">geo::Point</span> {
    <span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">pt</span>: <span class="ident">LonLat</span>) -&gt; <span class="self">Self</span> {
        <span class="ident">geo::Point::new</span>(<span class="ident">pt</span>.<span class="ident">x</span>(), <span class="ident">pt</span>.<span class="ident">y</span>())
    }
}
</code></pre></div>
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