generate.rs

//! Generate a file with an arbitrary number of rows.
//!
//! See reference implementation: https://github.com/gunnarmorling/1brc/blob/main/src/main/java/dev/morling/onebrc/CreateMeasurements.java

use anyhow::{anyhow, Context, Result};
use rand::seq::SliceRandom;
use rand_distr::{Distribution, Normal};
use std::io::Write;

fn main() -> Result<()> {
    let n = std::env::args()
        .nth(1)
        .ok_or_else(|| anyhow!("requires at least one argument"))?
        .parse::<usize>()
        .context("must be able to parse as usize")?;

    let mut rng = rand::thread_rng();

    let file =
        std::fs::File::create("measurements.txt").context("opening output file for write")?;
    let mut buf = std::io::BufWriter::new(file);

    let std_devs = Normal::new(10.0, 2.5).context("std_devs is valid normal distribution")?;
    let mut data = Vec::with_capacity(DATA.len());
    for (city, mean) in DATA.iter().copied() {
        let dist = Normal::new(mean, std_devs.sample(&mut rng))
            .context(anyhow!("creating new normal distribution for {city}"))?;
        data.push((city, dist));
    }

    for _ in 0..n {
        let (city, dist) = data.choose(&mut rng).expect("data is not empty");
        let temp = dist.sample(&mut rng);
        let temp = (temp * 10.0).round() / 10.0;
        writeln!(buf, "{city};{temp}").context("writing data line")?;
    }

    Ok(())
}

const DATA: &[(&str, f64)] = &[
    ("Abha", 18.0),
    ("Abidjan", 26.0),
    ("Abéché", 29.4),
    ("Accra", 26.4),
    ("Addis Ababa", 16.0),
    ("Adelaide", 17.3),
    ("Aden", 29.1),
    ("Ahvaz", 25.4),
    ("Albuquerque", 14.0),
    ("Alexandra", 11.0),
    ("Alexandria", 20.0),
    ("Algiers", 18.2),
    ("Alice Springs", 21.0),
    ("Almaty", 10.0),
    ("Amsterdam", 10.2),
    ("Anadyr", -6.9),
    ("Anchorage", 2.8),
    ("Andorra la Vella", 9.8),
    ("Ankara", 12.0),
    ("Antananarivo", 17.9),
    ("Antsiranana", 25.2),
    ("Arkhangelsk", 1.3),
    ("Ashgabat", 17.1),
    ("Asmara", 15.6),
    ("Assab", 30.5),
    ("Astana", 3.5),
    ("Athens", 19.2),
    ("Atlanta", 17.0),
    ("Auckland", 15.2),
    ("Austin", 20.7),
    ("Baghdad", 22.77),
    ("Baguio", 19.5),
    ("Baku", 15.1),
    ("Baltimore", 13.1),
    ("Bamako", 27.8),
    ("Bangkok", 28.6),
    ("Bangui", 26.0),
    ("Banjul", 26.0),
    ("Barcelona", 18.2),
    ("Bata", 25.1),
    ("Batumi", 14.0),
    ("Beijing", 12.9),
    ("Beirut", 20.9),
    ("Belgrade", 12.5),
    ("Belize City", 26.7),
    ("Benghazi", 19.9),
    ("Bergen", 7.7),
    ("Berlin", 10.3),
    ("Bilbao", 14.7),
    ("Birao", 26.5),
    ("Bishkek", 11.3),
    ("Bissau", 27.0),
    ("Blantyre", 22.2),
    ("Bloemfontein", 15.6),
    ("Boise", 11.4),
    ("Bordeaux", 14.2),
    ("Bosaso", 30.0),
    ("Boston", 10.9),
    ("Bouaké", 26.0),
    ("Bratislava", 10.5),
    ("Brazzaville", 25.0),
    ("Bridgetown", 27.0),
    ("Brisbane", 21.4),
    ("Brussels", 10.5),
    ("Bucharest", 10.8),
    ("Budapest", 11.3),
    ("Bujumbura", 23.8),
    ("Bulawayo", 18.9),
    ("Burnie", 13.1),
    ("Busan", 15.0),
    ("Cabo San Lucas", 23.9),
    ("Cairns", 25.0),
    ("Cairo", 21.4),
    ("Calgary", 4.4),
    ("Canberra", 13.1),
    ("Cape Town", 16.2),
    ("Changsha", 17.4),
    ("Charlotte", 16.1),
    ("Chiang Mai", 25.8),
    ("Chicago", 9.8),
    ("Chihuahua", 18.6),
    ("Chișinău", 10.2),
    ("Chittagong", 25.9),
    ("Chongqing", 18.6),
    ("Christchurch", 12.2),
    ("City of San Marino", 11.8),
    ("Colombo", 27.4),
    ("Columbus", 11.7),
    ("Conakry", 26.4),
    ("Copenhagen", 9.1),
    ("Cotonou", 27.2),
    ("Cracow", 9.3),
    ("Da Lat", 17.9),
    ("Da Nang", 25.8),
    ("Dakar", 24.0),
    ("Dallas", 19.0),
    ("Damascus", 17.0),
    ("Dampier", 26.4),
    ("Dar es Salaam", 25.8),
    ("Darwin", 27.6),
    ("Denpasar", 23.7),
    ("Denver", 10.4),
    ("Detroit", 10.0),
    ("Dhaka", 25.9),
    ("Dikson", -11.1),
    ("Dili", 26.6),
    ("Djibouti", 29.9),
    ("Dodoma", 22.7),
    ("Dolisie", 24.0),
    ("Douala", 26.7),
    ("Dubai", 26.9),
    ("Dublin", 9.8),
    ("Dunedin", 11.1),
    ("Durban", 20.6),
    ("Dushanbe", 14.7),
    ("Edinburgh", 9.3),
    ("Edmonton", 4.2),
    ("El Paso", 18.1),
    ("Entebbe", 21.0),
    ("Erbil", 19.5),
    ("Erzurum", 5.1),
    ("Fairbanks", -2.3),
    ("Fianarantsoa", 17.9),
    ("Flores,  Petén", 26.4),
    ("Frankfurt", 10.6),
    ("Fresno", 17.9),
    ("Fukuoka", 17.0),
    ("Gabès", 19.5),
    ("Gaborone", 21.0),
    ("Gagnoa", 26.0),
    ("Gangtok", 15.2),
    ("Garissa", 29.3),
    ("Garoua", 28.3),
    ("George Town", 27.9),
    ("Ghanzi", 21.4),
    ("Gjoa Haven", -14.4),
    ("Guadalajara", 20.9),
    ("Guangzhou", 22.4),
    ("Guatemala City", 20.4),
    ("Halifax", 7.5),
    ("Hamburg", 9.7),
    ("Hamilton", 13.8),
    ("Hanga Roa", 20.5),
    ("Hanoi", 23.6),
    ("Harare", 18.4),
    ("Harbin", 5.0),
    ("Hargeisa", 21.7),
    ("Hat Yai", 27.0),
    ("Havana", 25.2),
    ("Helsinki", 5.9),
    ("Heraklion", 18.9),
    ("Hiroshima", 16.3),
    ("Ho Chi Minh City", 27.4),
    ("Hobart", 12.7),
    ("Hong Kong", 23.3),
    ("Honiara", 26.5),
    ("Honolulu", 25.4),
    ("Houston", 20.8),
    ("Ifrane", 11.4),
    ("Indianapolis", 11.8),
    ("Iqaluit", -9.3),
    ("Irkutsk", 1.0),
    ("Istanbul", 13.9),
    ("İzmir", 17.9),
    ("Jacksonville", 20.3),
    ("Jakarta", 26.7),
    ("Jayapura", 27.0),
    ("Jerusalem", 18.3),
    ("Johannesburg", 15.5),
    ("Jos", 22.8),
    ("Juba", 27.8),
    ("Kabul", 12.1),
    ("Kampala", 20.0),
    ("Kandi", 27.7),
    ("Kankan", 26.5),
    ("Kano", 26.4),
    ("Kansas City", 12.5),
    ("Karachi", 26.0),
    ("Karonga", 24.4),
    ("Kathmandu", 18.3),
    ("Khartoum", 29.9),
    ("Kingston", 27.4),
    ("Kinshasa", 25.3),
    ("Kolkata", 26.7),
    ("Kuala Lumpur", 27.3),
    ("Kumasi", 26.0),
    ("Kunming", 15.7),
    ("Kuopio", 3.4),
    ("Kuwait City", 25.7),
    ("Kyiv", 8.4),
    ("Kyoto", 15.8),
    ("La Ceiba", 26.2),
    ("La Paz", 23.7),
    ("Lagos", 26.8),
    ("Lahore", 24.3),
    ("Lake Havasu City", 23.7),
    ("Lake Tekapo", 8.7),
    ("Las Palmas de Gran Canaria", 21.2),
    ("Las Vegas", 20.3),
    ("Launceston", 13.1),
    ("Lhasa", 7.6),
    ("Libreville", 25.9),
    ("Lisbon", 17.5),
    ("Livingstone", 21.8),
    ("Ljubljana", 10.9),
    ("Lodwar", 29.3),
    ("Lomé", 26.9),
    ("London", 11.3),
    ("Los Angeles", 18.6),
    ("Louisville", 13.9),
    ("Luanda", 25.8),
    ("Lubumbashi", 20.8),
    ("Lusaka", 19.9),
    ("Luxembourg City", 9.3),
    ("Lviv", 7.8),
    ("Lyon", 12.5),
    ("Madrid", 15.0),
    ("Mahajanga", 26.3),
    ("Makassar", 26.7),
    ("Makurdi", 26.0),
    ("Malabo", 26.3),
    ("Malé", 28.0),
    ("Managua", 27.3),
    ("Manama", 26.5),
    ("Mandalay", 28.0),
    ("Mango", 28.1),
    ("Manila", 28.4),
    ("Maputo", 22.8),
    ("Marrakesh", 19.6),
    ("Marseille", 15.8),
    ("Maun", 22.4),
    ("Medan", 26.5),
    ("Mek'ele", 22.7),
    ("Melbourne", 15.1),
    ("Memphis", 17.2),
    ("Mexicali", 23.1),
    ("Mexico City", 17.5),
    ("Miami", 24.9),
    ("Milan", 13.0),
    ("Milwaukee", 8.9),
    ("Minneapolis", 7.8),
    ("Minsk", 6.7),
    ("Mogadishu", 27.1),
    ("Mombasa", 26.3),
    ("Monaco", 16.4),
    ("Moncton", 6.1),
    ("Monterrey", 22.3),
    ("Montreal", 6.8),
    ("Moscow", 5.8),
    ("Mumbai", 27.1),
    ("Murmansk", 0.6),
    ("Muscat", 28.0),
    ("Mzuzu", 17.7),
    ("N'Djamena", 28.3),
    ("Naha", 23.1),
    ("Nairobi", 17.8),
    ("Nakhon Ratchasima", 27.3),
    ("Napier", 14.6),
    ("Napoli", 15.9),
    ("Nashville", 15.4),
    ("Nassau", 24.6),
    ("Ndola", 20.3),
    ("New Delhi", 25.0),
    ("New Orleans", 20.7),
    ("New York City", 12.9),
    ("Ngaoundéré", 22.0),
    ("Niamey", 29.3),
    ("Nicosia", 19.7),
    ("Niigata", 13.9),
    ("Nouadhibou", 21.3),
    ("Nouakchott", 25.7),
    ("Novosibirsk", 1.7),
    ("Nuuk", -1.4),
    ("Odesa", 10.7),
    ("Odienné", 26.0),
    ("Oklahoma City", 15.9),
    ("Omaha", 10.6),
    ("Oranjestad", 28.1),
    ("Oslo", 5.7),
    ("Ottawa", 6.6),
    ("Ouagadougou", 28.3),
    ("Ouahigouya", 28.6),
    ("Ouarzazate", 18.9),
    ("Oulu", 2.7),
    ("Palembang", 27.3),
    ("Palermo", 18.5),
    ("Palm Springs", 24.5),
    ("Palmerston North", 13.2),
    ("Panama City", 28.0),
    ("Parakou", 26.8),
    ("Paris", 12.3),
    ("Perth", 18.7),
    ("Petropavlovsk-Kamchatsky", 1.9),
    ("Philadelphia", 13.2),
    ("Phnom Penh", 28.3),
    ("Phoenix", 23.9),
    ("Pittsburgh", 10.8),
    ("Podgorica", 15.3),
    ("Pointe-Noire", 26.1),
    ("Pontianak", 27.7),
    ("Port Moresby", 26.9),
    ("Port Sudan", 28.4),
    ("Port Vila", 24.3),
    ("Port-Gentil", 26.0),
    ("Portland (OR)", 12.4),
    ("Porto", 15.7),
    ("Prague", 8.4),
    ("Praia", 24.4),
    ("Pretoria", 18.2),
    ("Pyongyang", 10.8),
    ("Rabat", 17.2),
    ("Rangpur", 24.4),
    ("Reggane", 28.3),
    ("Reykjavík", 4.3),
    ("Riga", 6.2),
    ("Riyadh", 26.0),
    ("Rome", 15.2),
    ("Roseau", 26.2),
    ("Rostov-on-Don", 9.9),
    ("Sacramento", 16.3),
    ("Saint Petersburg", 5.8),
    ("Saint-Pierre", 5.7),
    ("Salt Lake City", 11.6),
    ("San Antonio", 20.8),
    ("San Diego", 17.8),
    ("San Francisco", 14.6),
    ("San Jose", 16.4),
    ("San José", 22.6),
    ("San Juan", 27.2),
    ("San Salvador", 23.1),
    ("Sana'a", 20.0),
    ("Santo Domingo", 25.9),
    ("Sapporo", 8.9),
    ("Sarajevo", 10.1),
    ("Saskatoon", 3.3),
    ("Seattle", 11.3),
    ("Ségou", 28.0),
    ("Seoul", 12.5),
    ("Seville", 19.2),
    ("Shanghai", 16.7),
    ("Singapore", 27.0),
    ("Skopje", 12.4),
    ("Sochi", 14.2),
    ("Sofia", 10.6),
    ("Sokoto", 28.0),
    ("Split", 16.1),
    ("St. John's", 5.0),
    ("St. Louis", 13.9),
    ("Stockholm", 6.6),
    ("Surabaya", 27.1),
    ("Suva", 25.6),
    ("Suwałki", 7.2),
    ("Sydney", 17.7),
    ("Tabora", 23.0),
    ("Tabriz", 12.6),
    ("Taipei", 23.0),
    ("Tallinn", 6.4),
    ("Tamale", 27.9),
    ("Tamanrasset", 21.7),
    ("Tampa", 22.9),
    ("Tashkent", 14.8),
    ("Tauranga", 14.8),
    ("Tbilisi", 12.9),
    ("Tegucigalpa", 21.7),
    ("Tehran", 17.0),
    ("Tel Aviv", 20.0),
    ("Thessaloniki", 16.0),
    ("Thiès", 24.0),
    ("Tijuana", 17.8),
    ("Timbuktu", 28.0),
    ("Tirana", 15.2),
    ("Toamasina", 23.4),
    ("Tokyo", 15.4),
    ("Toliara", 24.1),
    ("Toluca", 12.4),
    ("Toronto", 9.4),
    ("Tripoli", 20.0),
    ("Tromsø", 2.9),
    ("Tucson", 20.9),
    ("Tunis", 18.4),
    ("Ulaanbaatar", -0.4),
    ("Upington", 20.4),
    ("Ürümqi", 7.4),
    ("Vaduz", 10.1),
    ("Valencia", 18.3),
    ("Valletta", 18.8),
    ("Vancouver", 10.4),
    ("Veracruz", 25.4),
    ("Vienna", 10.4),
    ("Vientiane", 25.9),
    ("Villahermosa", 27.1),
    ("Vilnius", 6.0),
    ("Virginia Beach", 15.8),
    ("Vladivostok", 4.9),
    ("Warsaw", 8.5),
    ("Washington, D.C.", 14.6),
    ("Wau", 27.8),
    ("Wellington", 12.9),
    ("Whitehorse", -0.1),
    ("Wichita", 13.9),
    ("Willemstad", 28.0),
    ("Winnipeg", 3.0),
    ("Wrocław", 9.6),
    ("Xi'an", 14.1),
    ("Yakutsk", -8.8),
    ("Yangon", 27.5),
    ("Yaoundé", 23.8),
    ("Yellowknife", -4.3),
    ("Yerevan", 12.4),
    ("Yinchuan", 9.0),
    ("Zagreb", 10.7),
    ("Zanzibar City", 26.0),
    ("Zürich", 9.3),
];