另一种有趣的方法是通过Pyodide和WebAssembly实现混合JavaScript和Python,使用Python的库Pandas和geographiclib来获得解决方案,这也是可行的。
我用Pandas做了额外的工作来准备输入数据,当输出可用时,将它们附加到解决方案列中。Pandas为常见需求提供了许多有用的输入/输出特性。它的toHtml方法可以方便地在网页上呈现最终的解决方案。
我发现这个答案中的代码在某些iPhone和iPad设备上执行不成功。但在较新的中端Android设备上,它运行得很好。
async function main(){
let pyodide = await loadPyodide();
await pyodide.loadPackage(["pandas", "micropip"]);
console.log(pyodide.runPythonAsync(`
import micropip
import pandas as pd
import js
print("Pandas version: " + pd.__version__)
await micropip.install('geographiclib')
from geographiclib.geodesic import Geodesic
import geographiclib as gl
print("Geographiclib version: " + gl.__version__)
data = {'Description': ['Answer to the question', 'Bangkok to Tokyo'],
'From_long': [21.0122287, 100.6],
'From_lat': [52.2296756, 13.8],
'To_long': [16.9251681, 139.76],
'To_lat': [52.406374, 35.69],
'Distance_km': [0, 0]}
df1 = pd.DataFrame(data)
collist = ['Description','From_long','From_lat','To_long','To_lat']
div2 = js.document.createElement("div")
div2content = df1.to_html(buf=None, columns=collist, col_space=None, header=True, index=True)
div2.innerHTML = div2content
js.document.body.append(div2)
arr="<i>by Swatchai</i>"
def dkm(frLat,frLon,toLat,toLon):
print("frLon,frLat,toLon,toLat:", frLon, "|", frLat, "|", toLon, "|", toLat)
dist = Geodesic.WGS84.Inverse(frLat, frLon, toLat, toLon)
return dist["s12"] / 1000
collist = ['Description','From_long','From_lat','To_long','To_lat','Distance_km']
dist = []
for ea in zip(df1['From_lat'].values, df1['From_long'].values, df1['To_lat'].values, df1['To_long'].values):
ans = dkm(*ea)
print("ans=", ans)
dist.append(ans)
df1['Distance_km'] = dist
# Update content
div2content = df1.to_html(buf=None, columns=collist, col_space=None, header=True, index=False)
div2.innerHTML = div2content
js.document.body.append(div2)
# Using the haversine formula
from math import sin, cos, sqrt, atan2, radians, asin
# Approximate radius of earth in km from Wikipedia
R = 6371
lat1 = radians(52.2296756)
lon1 = radians(21.0122287)
lat2 = radians(52.406374)
lon2 = radians(16.9251681)
# https://en.wikipedia.org/wiki/Haversine_formula
def hav(angrad):
return (1-cos(angrad))/2
h = hav(lat2-lat1)+cos(lat2)*cos(lat1)*hav(lon2-lon1)
dist2 = 2*R*asin(sqrt(h))
print(f"Distance by haversine formula = {dist2:8.6f} km.")
`));
}
main();
<script src="https://cdn.jsdelivr.net/pyodide/v0.21.0/full/pyodide.js"></script>
Pyodide implementation<br>