在数据框

Question

所以我有这个例子df：

df <- dput(structure(list(arts = structure(c(1L, 1L, 3L, 4L), .Label = c("art1", "art2"), class = "character"), scr1 = c(52L, 58L, 40L, 62L), scr2 = c(25L, 23L, 55L, 26L), scr3 = c(36L, 60L, 19L, 22L)), .Names = c("art_id", "scr1", "scr2", "scr3"), row.names = c(NA, -4L), class = "data.frame"))

> df
  art_id scr1 scr2 scr3
1      1   52   25   36
2      1   58   23   60
3      3   40   55   19
4      4   62   26   22

我正在使用dplyr按art_id

进行汇总

df %>% 
  group_by(art_id) %>% 
  summarise_each(funs(sum))

  art_id  scr1  scr2  scr3
   <int> <int> <int> <int>
1      1   110    48    96
2      3    40    55    19
3      4    62    26    22

我的问题：如何添加另一个名为top_r的列，其中包含src1:src3中最大的列名。结果df看起来像：

  art_id  scr1  scr2  scr3  top_r
   <int> <int> <int> <int>  <char>
1      1   110    48    96   scr1  
2      3    40    55    19   scr2  
3      4    62    26    22   scr1  

我很自在地使用dplyr所以如果有一个答案使用那个很棒的库！

Answer 1

在基础R中使用max.col：

就是这么简单

df$top_r <- names(df)[-1][max.col(df[-1])]

Answer 2

这样可行：

df %>%
  group_by(art_id) %>%
  summarise_each(funs(sum)) %>%
  mutate(top_r=apply(.[,2:4], 1, function(x) names(x)[which.max(x)]))

# A tibble: 3 × 5
  art_id  scr1  scr2  scr3 top_r
   <int> <int> <int> <int> <chr>
1      1   110    48    96  scr1
2      3    40    55    19  scr2
3      4    62    26    22  scr1

Answer 3

library(dplyr)
library(tidyr)

df2 <- df %>% 
  group_by(art_id) %>% 
  summarise_each(funs(sum))

df3 <- df2 %>%
  gather(top_r, Value, -art_id) %>%
  arrange(art_id, desc(Value)) %>%
  group_by(art_id) %>%
  slice(1) %>%
  select(-Value)

df_final <- df2 %>%
  left_join(df3, by = "art_id")

df_final
# A tibble: 3 × 5
  art_id  scr1  scr2  scr3 top_r
   <int> <int> <int> <int> <chr>
1      1   110    48    96  scr1
2      3    40    55    19  scr2
3      4    62    26    22  scr1