我有一个Express Node.js应用程序,但我也有一个机器学习算法在Python中使用。是否有一种方法可以从我的Node.js应用程序调用Python函数来利用机器学习库的强大功能?
当前回答
/*eslint-env es6*/
/*global require*/
/*global console*/
var express = require('express');
var app = express();
// Creates a server which runs on port 3000 and
// can be accessed through localhost:3000
app.listen(3000, function() {
console.log('server running on port 3000');
} )
app.get('/name', function(req, res) {
console.log('Running');
// Use child_process.spawn method from
// child_process module and assign it
// to variable spawn
var spawn = require("child_process").spawn;
// Parameters passed in spawn -
// 1. type_of_script
// 2. list containing Path of the script
// and arguments for the script
// E.g : http://localhost:3000/name?firstname=Levente
var process = spawn('python',['apiTest.py',
req.query.firstname]);
// Takes stdout data from script which executed
// with arguments and send this data to res object
var output = '';
process.stdout.on('data', function(data) {
console.log("Sending Info")
res.end(data.toString('utf8'));
});
console.log(output);
});
这对我很管用。必须将python.exe添加到此代码段的路径变量中。另外,确保你的python脚本在你的项目文件夹中。
其他回答
通过extrabacon, Python -shell模块是一种从Node.js运行Python脚本的简单方法,具有基本但有效的进程间通信和更好的错误处理。
安装:
npm: NPM安装python-shell。
或者用纱线: 纱线加蟒壳
运行一个简单的Python脚本:
const PythonShell = require('python-shell').PythonShell;
PythonShell.run('my_script.py', null, function (err) {
if (err) throw err;
console.log('finished');
});
运行带有参数和选项的Python脚本:
const PythonShell = require('python-shell').PythonShell;
var options = {
mode: 'text',
pythonPath: 'path/to/python',
pythonOptions: ['-u'],
scriptPath: 'path/to/my/scripts',
args: ['value1', 'value2', 'value3']
};
PythonShell.run('my_script.py', options, function (err, results) {
if (err)
throw err;
// Results is an array consisting of messages collected during execution
console.log('results: %j', results);
});
要获得完整的文档和源代码,请访问https://github.com/extrabacon/python-shell
我在节点10和子进程1.0.2上。来自python的数据是一个字节数组,必须进行转换。这是另一个用python发出http请求的快速示例。
node
const process = spawn("python", ["services/request.py", "https://www.google.com"])
return new Promise((resolve, reject) =>{
process.stdout.on("data", data =>{
resolve(data.toString()); // <------------ by default converts to utf-8
})
process.stderr.on("data", reject)
})
request.py
import urllib.request
import sys
def karl_morrison_is_a_pedant():
response = urllib.request.urlopen(sys.argv[1])
html = response.read()
print(html)
sys.stdout.flush()
karl_morrison_is_a_pedant()
p.s.不是一个人为的例子,因为节点的http模块不加载我需要做的一些请求
之前的大多数答案都将承诺的成功称为on(“数据”),这不是正确的方法,因为如果你收到很多数据,你只会得到第一部分。相反,你必须在end事件上做。
const { spawn } = require('child_process');
const pythonDir = (__dirname + "/../pythonCode/"); // Path of python script folder
const python = pythonDir + "pythonEnv/bin/python"; // Path of the Python interpreter
/** remove warning that you don't care about */
function cleanWarning(error) {
return error.replace(/Detector is not able to detect the language reliably.\n/g,"");
}
function callPython(scriptName, args) {
return new Promise(function(success, reject) {
const script = pythonDir + scriptName;
const pyArgs = [script, JSON.stringify(args) ]
const pyprog = spawn(python, pyArgs );
let result = "";
let resultError = "";
pyprog.stdout.on('data', function(data) {
result += data.toString();
});
pyprog.stderr.on('data', (data) => {
resultError += cleanWarning(data.toString());
});
pyprog.stdout.on("end", function(){
if(resultError == "") {
success(JSON.parse(result));
}else{
console.error(`Python error, you can reproduce the error with: \n${python} ${script} ${pyArgs.join(" ")}`);
const error = new Error(resultError);
console.error(error);
reject(resultError);
}
})
});
}
module.exports.callPython = callPython;
电话:
const pythonCaller = require("../core/pythonCaller");
const result = await pythonCaller.callPython("preprocessorSentiment.py", {"thekeyYouwant": value});
python:
try:
argu = json.loads(sys.argv[1])
except:
raise Exception("error while loading argument")
许多例子都是过时的,并且涉及复杂的设置。您可以尝试JSPyBridge/pythonia(完全披露:我是作者)。它是一种普通的JS,可以让你操作外部Python对象,就好像它们存在于JS中一样。事实上,它实现了互操作性,因此Python代码可以通过回调和传递函数返回调用JS。
numpy + matplotlib的例子,用ES6导入系统:
import { py, python } from 'pythonia'
const np = await python('numpy')
const plot = await python('matplotlib.pyplot')
// Fixing random state for reproducibility
await np.random.seed(19680801)
const [mu, sigma] = [100, 15]
// Inline expression evaluation for operator overloading
const x = await py`${mu} + ${sigma} * ${np.random.randn(10000)}`
// the histogram of the data
const [n, bins, patches] = await plot.hist$(x, 50, { density: true, facecolor: 'g', alpha: 0.75 })
console.log('Distribution', await n) // Always await for all Python access
await plot.show()
python.exit()
通过CommonJS(没有顶级await):
const { py, python } = require('pythonia')
async function main() {
const np = await python('numpy')
const plot = await python('matplotlib.pyplot')
...
// the rest of the code
}
main().then(() => python.exit()) // If you don't call this, the process won't quit by itself.
你可以把你的python编译,然后像调用javascript一样调用它。我已经成功地为screeps做了这件事,甚至让它在浏览器中运行la brython。
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