stevens-parser.js

var fs = require("fs");

var table = read_table("data/hurdat2-1851-2017-050118.txt", ",");

var curr_obj,
curr_entry_count;

var data = [],
    geojson = {
        "type": "FeatureCollection",
        "features": []
    };

// See: https://www.nhc.noaa.gov/data/hurdat/hurdat2-format-atlantic.pdf
table.forEach(line = > {
    // Parse the header line
    if (line.length === 3) {
        curr_entry_count = 0;
        curr_obj = {
            data: []
        };

        curr_obj.basin = line.cells[0].slice(0, 2);
        curr_obj.number = line.cells[0].slice(2, 4);
        curr_obj.year = +line.cells[0].slice(4, 8);
        curr_obj.name = line.cells[1];
        curr_obj.entries = line.cells[2];
    }

    // Parse the data line
    else {
        curr_entry_count++;

        var o = {
            year: line.cells[0].slice(0, 4),
            month: line.cells[0].slice(4, 6),
            day: line.cells[0].slice(6, 8),
            hour: line.cells[1].slice(0, 2),
            minute: line.cells[1].slice(2, 4),
            record_identifier: line.cells[2],
            status_of_system: line.cells[3],
            latitude: parse_coord(line.cells[4]),
            longitude: parse_coord(line.cells[5]),
            maximum_sustained_wind: +line.cells[6],
            minimum_pressure: line.cells[7]
        };

        curr_obj.data.push(o);
        if (curr_entry_count == curr_obj.entries) {
            data.push(curr_obj);
        }
    }

});

data.forEach(d0 = > {
    d0.statuses_of_system = uniqueBy(d0.data, "status_of_system");
    d0.maximum_sustained_wind = max(d0.data.map(m = > m.maximum_sustained_wind));

    var keys_0 = Object.keys(d0);
    keys_0.shift();
    var keys_1 = Object.keys(d0.data[0]);

    d0.data.forEach((d1, i1) = > {

        if (i1 < d0.data.length - 1) {
            var geojson_obj = {
                "type": "Feature",
                "geometry": {
                    "type": "LineString",
                    "coordinates": []
                },
                "properties": {}
            }

            keys_0.forEach(k = > {
                geojson_obj.properties[k] = d0[k];
            });
            keys_1.forEach(k = > {
                geojson_obj.properties[k] = d1[k];
            });

            geojson_obj.geometry.coordinates = [
                [d1.longitude, d1.latitude],
                [d0.data[i1 + 1].longitude, d0.data[i1 + 1].latitude]
            ];

            geojson.features.push(geojson_obj);
        }
    });

    return d0;
});

fs.writeFileSync("output/historical-hurricanes.json", JSON.stringify(data));
fs.writeFileSync("output/historical-hurricanes.geo.json", JSON.stringify(geojson));

function parse_coord(n) {
    var s = n.split("");
    var cardinal = s.pop();
    var number = +s.join("");

    return ["W", "S"].includes(cardinal) ? 0 - number : number;
}

function read_table(file_name, delimiter) {
    var file_txt = fs.readFileSync(file_name, "utf8");
    var lines = file_txt.split("\n").map(d = > {
        var c = d.split(delimiter).map(t = > t.trim());
        c.pop();
        return {
            cells: c,
            length: c.length
        }
    });
    lines.pop();
    return lines;
}

function max(arr) {
    return arr.reduce((a, b) = > Math.max(a, b));
}

function pluck(arr, attribute) {
    return arr.map(d = > d[attribute]);
}

function unique(arr) {
    return arr.filter((value, index, self) = > self.indexOf(value) === index);
}

function uniqueBy(arr, attribute) {
    return unique(pluck(arr, attribute));
}