未找到對象錯誤功能

Question

我做了這個功能，其目的是輸出的協方差分析的總結得出結果：

statAncova <- function (dataframe, response, covariate, Factor) { 

    library(ggplot2) 
    mod <- aov(response ~ covariate + Factor, data=dataframe) 
    pred <- predict(mod) 
    plotMod <- ggplot(data = cbind(mod$model, pred), aes(covariate, response, color=Factor)) + 
    geom_point() + 
    facet_grid(. ~ Factor) + 
    geom_line(aes(y=pred)) 

    return(list(mod, plotMod)) 

} 

如果我嘗試使用功能是這樣的：

statAncova(mtcars, drat, hp, cyl) 

我得到這個錯誤：

Error in eval(expr, envir, enclos) : object 'drat' not found 

我在做什麼錯？

Answer 1

R期待在該環境中有一個名爲'drat'的對象，但'drat'是數據幀mtcars的成員。

我知道可能有一個更優雅的解決方案，但解決它是使用一種方法：

statAncova <- function (dataframe, response, covariate, Factor) { 

    library(ggplot2) 
    eval(parse(text=paste0("mod <- aov(",response," ~ ",covariate," + ",Factor,", data=dataframe)"))) 
    pred <- predict(mod) 
    eval(parse(text=paste0("plotMod <- ggplot(data = cbind(mod$model, pred), aes(",covariate,", ",response,", color=",Factor,")) + 
    geom_point() + 
    facet_grid(. ~ ",Factor,") + 
    geom_line(aes(y=pred))"))) 

    return(list(mod, plotMod)) 

} 

statAncova(mtcars, "drat", "hp", "cyl") 

或者，你可以只通過您感興趣的各變量：

statAncova <- function (response, covariate, Factor) { 

    dataframe <- data.frame(response, covariate, Factor) 

    library(ggplot2) 
    mod <- aov(response ~ covariate + Factor, data=dataframe) 
    pred <- predict(mod) 
    plotMod <- ggplot(data = cbind(mod$model, pred), aes(covariate, response, color=Factor)) + 
    geom_point() + 
    facet_grid(. ~ Factor) + 
    geom_line(aes(y=pred)) 

    return(list(mod, plotMod)) 

} 

statAncova(mtcars$drat, mtcars$hp, mtcars$cyl)