Alex Yatskov
c4771359bd
git-subtree-dir: build git-subtree-mainline:c63c6a835fgit-subtree-split:9d3fe8f2ed
74 lines
2.1 KiB
Go
74 lines
2.1 KiB
Go
/*
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* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
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* Author: Alex Yatskov <alex@foosoft.net>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package main
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import (
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"encoding/json"
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"math"
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"os"
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"github.com/kellydunn/golang-geo"
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)
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type station struct {
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Latitude float64
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Longitude float64
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}
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type stationQuery struct {
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stations map[string]station
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}
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func newStationQuery(filename string) (*stationQuery, error) {
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s := new(stationQuery)
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file, err := os.Open(filename)
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if err != nil {
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return nil, err
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}
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defer file.Close()
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if err := json.NewDecoder(file).Decode(&s.stations); err != nil {
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return nil, err
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}
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return s, nil
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}
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func (s *stationQuery) closestStation(latitude, longitude float64) (name string, distance float64) {
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queryPt := geo.NewPoint(latitude, longitude)
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var closestStn string
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minDist := math.MaxFloat64
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for name, station := range s.stations {
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stnPt := geo.NewPoint(station.Latitude, station.Longitude)
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if currDist := queryPt.GreatCircleDistance(stnPt); currDist < minDist {
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closestStn = name
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minDist = currDist
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}
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}
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return closestStn, minDist
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}
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