Question

我无法理解下面R脚本中出现的问题。在调用fct_expand之前定义变量级别会导致编译成功，但是当我将定义直接插入fct_expand时，R会产生错误

“mutate_impl（.data，dots）中的错误：尝试应用非函数”

R-script复制错误（Microsoft R open 3.4.0.0和R 3.3.3）：

library(dplyr)
library(forcats)
library(magrittr)

f <- factor(1:3)%>% tbl_df
f_lev <- factor(1:6) %>% tbl_df

#This compiles just fine
levels <- f_lev %$% value %>% levels
f %>% mutate(value = fct_expand(value, levels)) %$% value %>% levels

#This wont compile
f %>% mutate(value = fct_expand(value, f_lev %$% value %>% levels)) %$% value %>% levels

编辑：代码不会在试图运行R 3.3.3的4台机器中的3台上运行（没有错误的计算机从未安装过RTVS或Microsoft R。）。所以它必须依赖于我猜的一些设置。以下示例说明了同样的问题;在上面给出错误的机器上的代码如下：

library(dplyr)
library(forcats)
library(magrittr)

f <- factor(1:3) %>% tbl_df
f_lev <- factor(1:6) %>% tbl_df

f %>% {
   tmp <- f_lev %$% value %>% levels
   mutate(., value = fct_expand(value, tmp))
       } %>% str

f %>% {
mutate(., value = fct_expand(value, f_lev %$% value %>% levels))
      } %>% str

产生两种不同的结果：

Classes 'tbl_df', 'tbl' and 'data.frame':   3 obs. of  1 variable:
$ value: Factor w/ 6 levels "1","2","3","4",..: 1 2 3
Classes 'tbl_df', 'tbl' and 'data.frame':   3 obs. of  1 variable:
$ value: Factor w/ 3 levels "1","2","3": 1 2 3

在没有给出编译错误的计算机上，后一个代码导致：

Classes 'tbl_df', 'tbl' and 'data.frame':   3 obs. of  1 variable:
$ value: Factor w/ 6 levels "1","2","3","4",..: 1 2 3
Classes 'tbl_df', 'tbl' and 'data.frame':   3 obs. of  1 variable:
$ value: Factor w/ 6 levels "1","2","3","4",..: 1 2 3

单行中的多个管道不会编译

0 个答案: