Question

我已经构建了一个函数，我希望从数据框传递数据框和列。例如：

testdf <- structure(list(date = c("2016-04-04", "2016-04-04", "2016-04-04", 
"2016-04-04", "2016-04-04", "2016-04-04"), sensorheight = c(1L, 
16L, 1L, 16L, 1L, 16L), farm = c("McDonald", "McDonald", "McDonald", 
"McDonald", "McDonald", "McDonald"), location = c("4", "4", "5", 
"5", "Outside", "Outside"), Temp = c(122.8875, 117.225, 102.0375, 
98.3625, 88.5125, 94.7)), .Names = c("date", "sensorheight", 
"farm", "location", "Temp"), row.names = c(NA, 6L), class = "data.frame")

> testdf
        date sensorheight     farm location     Temp
1 2016-04-04            1 McDonald        4 122.8875
2 2016-04-04           16 McDonald        4 117.2250
3 2016-04-04            1 McDonald        5 102.0375
4 2016-04-04           16 McDonald        5  98.3625
5 2016-04-04            1 McDonald  Outside  88.5125
6 2016-04-04           16 McDonald  Outside  94.7000

该函数根据不同列中的值从其他值中减去一些值。它正在工作，接受数据框和列输入，但自更新R以来，它无效。

DailyInOutDiff <- function (df, variable) {

  DailyInOutDiff04 <- df %>%
    filter(location %in% c(4, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else variable[location=="4"] - variable[location=='Outside'], 
              location = "4")  %>%
    select(1, 2, 3, 5, 4)

  DailyInOutDiff05 <- df %>%
    filter(location %in% c(5, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else variable[location=="5"] - variable[location=='Outside'], 
              location = "5")  %>%
    select(1, 2, 3, 5, 4)

  temp.list <- list(DailyInOutDiff04, DailyInOutDiff05)
  final.df = bind_rows(temp.list)
  return(final.df)
}

test <- DailyInOutDiff(testdf, "Temp")
test <- DailyInOutDiff(testdf, quote(Temp))

他们会产生以下错误消息：

  Error in summarise_impl(.data, dots) : 
  Evaluation error: non-numeric argument to binary operator.

和

  Error in summarise_impl(.data, dots) : 
  Evaluation error: object of type 'symbol' is not subsettable.

我想知道这些错误消息的含义以及如何解决它们。

我尝试了这些解决方案Pass a data.frame column name to a function，但是这些解决方案都不适用于我。

如果我将列作为输入删除，则不会发生错误，但我需要该列，因为我将该函数应用于大型数据框中的多个列。

我想要的输出：

        date sensorheight     farm location     Temp
1 2016-04-04            1 McDonald        4  34.3750
2 2016-04-04           16 McDonald        4  22.5250
3 2016-04-04            1 McDonald        5  13.5250
4 2016-04-04           16 McDonald        5   3.6625

Answer 1

我无法复制第二个错误，但我可以复制第一个错误。 summarise函数似乎无法调用Temp，因为它认为它是character对象。换句话说，您正在调用列名，而不是列。如果您逐行在函数内运行代码，而不是使用variable df$variable，则会看到它有效。

话虽如此，解决方案非常简单。我刚刚在你的函数中添加了行variable<- as.name(variable)。现在它写着：

DailyInOutDiff <- function (df, variable) {

  variable<- as.name(variable)
  DailyInOutDiff04 <- df %>%
    filter(location %in% c(4, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else variable[location=="4"] - variable[location=='Outside'], 
              location = "4")  %>%
    select(1, 2, 3, 5, 4)

  DailyInOutDiff05 <- df %>%
    filter(location %in% c(5, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else variable[location=="5"] - variable[location=='Outside'], 
              location = "5")  %>%
    select(1, 2, 3, 5, 4)

  temp.list <- list(DailyInOutDiff04, DailyInOutDiff05)
  final.df = bind_rows(temp.list)
  return(final.df)
}

输出是：

> test <- DailyInOutDiff(testdf, "Temp")
> test
Source: local data frame [4 x 5]
Groups: date, sensorheight [2]

        date sensorheight     farm location    Diff
       <chr>        <int>    <chr>    <chr>   <dbl>
1 2016-04-04            1 McDonald        4 34.3750
2 2016-04-04           16 McDonald        4 22.5250
3 2016-04-04            1 McDonald        5 13.5250
4 2016-04-04           16 McDonald        5  3.6625

Answer 2

如果您使用的是最新的dplyr（0.7），则可以使用.data通过字符串引用列名称，您的函数将被修改为：

DailyInOutDiff <- function (df, variable) {

  DailyInOutDiff04 <- df %>%
    filter(location %in% c(4, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else .data[[variable]][location=="4"] - .data[[variable]][location=='Outside'], 
              location = "4")  %>%
    select(1, 2, 3, 5, 4)

  DailyInOutDiff05 <- df %>%
    filter(location %in% c(5, 'Outside')) %>% 
    group_by(date, sensorheight, farm) %>%
    arrange(sensorheight, farm, location) %>%
    summarise(Diff = if(n()==1) NA else .data[[variable]][location=="5"] - .data[[variable]][location=='Outside'], 
              location = "5")  %>%
    select(1, 2, 3, 5, 4)

  temp.list <- list(DailyInOutDiff04, DailyInOutDiff05)
  final.df = bind_rows(temp.list)
  return(final.df)
}

从variable[...]到.data[[variable]][...]的更改意味着它现在选择variable中字符串指定的列，而不是尝试索引实际字符串。使用提供的数据运行此函数将返回：

DailyInOutDiff(testdf, "Temp")
#> # A tibble: 4 x 5
#> # Groups:   date, sensorheight [2]
#>         date sensorheight     farm location    Diff
#>        <chr>        <int>    <chr>    <chr>   <dbl>
#> 1 2016-04-04            1 McDonald        4 34.3750
#> 2 2016-04-04           16 McDonald        4 22.5250
#> 3 2016-04-04            1 McDonald        5 13.5250
#> 4 2016-04-04           16 McDonald        5  3.6625

Answer 3

以下调用函数DailyInOutDiff并将 testdf 分配给 df ，将＆＃34; Temp＆＃34; 分配给变量< / strong>即可。

test <- DailyInOutDiff(testdf, "Temp") test <- DailyInOutDiff(testdf, quote(Temp))

根据您要执行的操作，您希望从数据框传递数据框和列。目前，您只传递列名称，这是一个字符串，而不是列。您必须将其更改为

test <- DailyInOutDiff(testdf, testdf["Temp"])

其次，您正在传递 Temp 列，并尝试根据以下代码段中的位置过滤变量数据框。

总结（Diff = if（n（）== 1）NA else变量[location ==＆＃34; 4＆＃34;] - 变量[location ==＆＃39; Outside＆＃39;]， location =＆＃34; 4＆＃34;）

一定是，

variable[variable$location=="4",]

如果您的电话是，

test <- DailyInOutDiff(testdf, testdf["Temp"])

或

variable[variable$Temp=="4",]

如果你打电话是，

test <- DailyInOutDiff(testdf, testdf["Temp"])

函数不接受列调用

3 个答案: