我正在寻找循环中几个数据帧的子集变量，将数据帧保存为子集之前的相同名称。名称遵循以下结构：rx.2003，rx.2004，rx.2005等。
我很难找到一个解决方案，以便在循环中正确地将数据集中。下面的代码产生以下错误：
//Initiallising node modules
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var sql = require("mssql");
var form = require('multer');
// Body Parser Middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
var urlencodedParser = bodyParser.urlencoded({ extended: false });
app.use(bodyParser.text({ type: 'text/html' }));
//CORS Middleware
app.use(function (req, res, next) {
//Enabling CORS
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, contentType,Content-Type, Accept, Authorization");
next();
});
//Setting up server
var server = app.listen(process.env.PORT || 8080, function () {
var port = server.address().port;
console.log("App now running on port", port);
});
// Configure database connection
var dbConfig = {
user: 'user',
domain: 'domain',
password: 'password',
server: 'server',
database: 'database'
};
//Function to connect to database and execute query
var executeQuery = function(res, query){
sql.connect(dbConfig, function (err) {
if (err) {
console.log("Error while connecting database :- " + err);
res.send(err);
}
else {
// create Request object
var request = new sql.Request();
// query to the database
request.query(query, function (err, rs) {
if (err) {
console.log("Error while querying database :- " + err);
res.send(err);
}
else {
res.send(rs);
sql.close();
}
});
}
});
};
//GET API
app.get("/api/user", function(req , res){
var query = "select * from [Names]";
executeQuery (res, query);
});
// //POST API
app.post('/api/user', function (req, res) {
res.setHeader('Content-Type', 'text/plain');
// connect to your database
sql.connect(dbConfig, function (err) {
if (err) console.log(err);
// create Request object
var request = new sql.Request();
request.input('first_name',sql.VarChar,req.body.first_name);
request.input('last_name',sql.VarChar,req.body.last_name);
request.input('gender',sql.VarChar,req.body.gender);
request.query("INSERT INTO Names (First_Name, Last_Name, Gender) VALUES (@first_name, @last_name, @gender)", function (err, recordset) {
if (err) console.log(err);
// send records as a response
res.send(recordset);
sql.close();
});
});
});
// //POST API
// app.post("/api/user", function(req , res){
// //var query = "INSERT INTO Names (First_Name, Last_Name, Gender) VALUES ('Test', 'User', 'Female')";
// var query = "INSERT INTO Names (First_Name,Last_Name,Gender) VALUES ()";
// executeQuery (res, query);
// });
//PUT API
app.put("/api/user/:id", function(req , res){
var query = "UPDATE [Names] SET First_Name= " + req.body.first_name + " , Last_Name= " + req.body.last_name + " , Gender= " + req.body.gender + " WHERE Id= " + req.params.id;
executeQuery (res, query);
});
// DELETE API
app.delete("/api/user/:id", function(req , res){
var query = "DELETE FROM [Names] WHERE Id=" + req.params.id;
executeQuery (res, query);
});
Error in ... target of assignment expands to non-language object
我知道这个错误表明R认为我要求它将文本＆＃34; rx.2003＆＃34;的子集，但我想弄清楚如何指示R到子集数据帧本身。
建议？
答案 0 :(得分：0)
也许你可以试试
for(i in 2003:2015)
{
DF <- get(paste0("rx.",i))
assign(paste0("rx.",i),subset(DF,select = c("ID", "Drug", "Year")
}
希望这有帮助