Question

我尝试编写一个函数，根据另一列的值计算一列（结果）的比例。代码如下所示：

thresh_measure <- function(data, indicator, thresh_value)
{
   d1 <- data %>% 
    group_by(class_number, outcome) %>%
    summarize(n=sum(indicator <= thresh_value)) %>% spread(outcome, n)
    d1$thresh_value <- thresh_value
    return(d1)
}

final_test <- thresh_measure(df, 'pass_rate', 0.8)

总结函数似乎有一个错误，其中当前函数返回所有0。当我改变它看起来像这样，它的工作原理：

thresh_measure <- function(data, indicator, thresh_value)
{
   d1 <- data %>% 
    group_by(class_number, outcome) %>%
    summarize(n=sum(pass_rate <= thresh_value)) %>% spread(outcome, n)
    d1$thresh_value <- thresh_value
    return(d1)
}

final_test <- thresh_measure(df, 'pass_rate', 0.8)

我已经尝试使用.GlobalEnv设置值，除了dplyr之外我还分离了所有库，但它仍然无法正常工作。

Answer 1

您必须处理要作为参数传递的列的名称。例如（当然存在更好的方法）：

thresh_measure <- function(data, indicator, thresh_value)
{
  d1 <- data
 names(d1)[names(d1)==indicator] <- "indicator"
  d1 <- d1 %>% 
    group_by(class_number, outcome)  %>%
    summarize(n=sum(indicator <= thresh_value))  %>% spread(outcome, n)

   d1$thresh_value <- thresh_value
  return(d1)
}

Answer 2

应该采用的两种替代方法：

# alternative I
thresh_measure <- function(data, indicator, thresh_value)
{
    ind_quo <- rlang::sym(indicator)
    d1 <- data %>%
        group_by(class_number, outcome) %>%
        summarize(n=sum(UQ(ind_quo) <= thresh_value)) %>% spread(outcome, n)
    d1$thresh_value <- thresh_value
    return(d1)
}

final_test <- thresh_measure(df, 'pass_rate', 0.8)

# alternative II
thresh_measure <- function(data, indicator, thresh_value)
{
    ind_quo <- enquo(indicator)
    d1 <- data %>%
        group_by(class_number, outcome) %>%
        summarize(n=sum(UQ(ind_quo) <= thresh_value)) %>% spread(outcome, n)
    d1$thresh_value <- thresh_value
    return(d1)
}

final_test <- thresh_measure(df, pass_rate, 0.8)

dplyr总结了不使用全局环境变量的函数

2 个答案: