如何使用 poly R 函数更改 for 循环中的多项式阶数？

Question

我想通过尝试不同的多项式来拟合回归，并且我尝试了运行这个循环：

for (p_order  in 1:9) {
  assign(paste("RD0", p_order, sep = ""),  electricity_price ~ d1 + gas_price + coal_price +
  oil_price + EUA +  weekday + month + median_windspeed1 + 
  median_windspeed2 +   median_windspeed3 +   median_windspeed4 + 
  sun1 + sun2 + sun3 + sun4 + median_temp1 +   median_temp2 + 
  median_temp3 + median_temp4 + poly(as.numeric(date), p_order, raw=TRUE) + time) 
}

虽然它正确地创建了变量的名称（RD01、RD02 等），但它没有保存多项式的正确顺序（1,2 等），而是存储 "p_order" 。例如，

> RD04
electricity_price ~ d1 + gas_price + coal_price + oil_price + 
    EUA + weekday + month + median_windspeed1 + median_windspeed2 + 
    median_windspeed3 + median_windspeed4 + sun1 + sun2 + sun3 + 
    sun4 + median_temp1 + median_temp2 + median_temp3 + median_temp4 + 
    poly(as.numeric(date), p_order, raw = TRUE) + time
> RD07
electricity_price ~ d1 + gas_price + coal_price + oil_price + 
    EUA + weekday + month + median_windspeed1 + median_windspeed2 + 
    median_windspeed3 + median_windspeed4 + sun1 + sun2 + sun3 + 
    sun4 + median_temp1 + median_temp2 + median_temp3 + median_temp4 + 
    poly(as.numeric(date), p_order, raw = TRUE) + time

有人可以向我解释为什么以及如何解决这个问题吗？

谢谢！

Answer 1

先创建公式，再赋值。我会post一个简化的例子。

for (p_order  in 1:2) {
  fmla <- paste("electricity_price ~ d1 + poly(as.numeric(date),", p_order, ", raw = TRUE)")
  assign(paste("RD0", p_order, sep = ""),  as.formula(fmla)) 
}

RD01
#electricity_price ~ d1 + poly(as.numeric(date), 1, raw = TRUE)
RD02
#electricity_price ~ d1 + poly(as.numeric(date), 2, raw = TRUE)

如何使用 poly R 函数更改 for 循环中的多项式阶数？

How to change the polynomial order in a for-loop using the poly R function?

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