dplyr 根据某些条件创建新列

2024-05-20 • 问答

我有以下 df：

df<-data.frame(geo_num=c(11,12,22,41,42,43,77,71),cust_id=c("A","A","B","C","D","D"),sales=c(2,3,2,1,4,6,3))
> df
  geo_num cust_id sales
1      11       A     2
2      12       A     3
3      22       B     2
4      41       C     1
5      42       C     2
6      43       C     4
7      77       D     6
8      71       D     3

需要创建一个新列 'geo_num_new'，其中每个组的 'cust_id' 都具有来自 'geo_num' 的第一个值，如下所示：

> df_new
  geo_num cust_id sales geo_num_new
1      11       A     2          11
2      12       A     3          11
3      22       B     2          22
4      41       C     1          41
5      42       C     2          41
6      43       C     4          41
7      77       D     6          77
8      71       D     3          77

谢谢。

我们可以在按“cust_id”分组后使用 first。单个值将被整个分组回收

library(dplyr)
df <- df %>% 
    group_by(cust_id) %>%
    mutate(geo_num_new = first(geo_num)) %>%
    ungroup

-输出

df
# A tibble: 8 x 4
  geo_num cust_id sales geo_num_new
    <dbl> <chr>   <dbl>       <dbl>
1      11 A           2          11
2      12 A           3          11
3      22 B           2          22
4      41 C           1          41
5      42 C           2          41
6      43 C           4          41
7      77 D           6          77
8      71 D           3          77

或使用 data.table

library(data.table)
setDT(df)[,geo_num_new := first(geo_num),by = cust_id]

或使用 base R

df$geo_num_new <- with(df,ave(geo_num,cust_id,FUN = function(x) x[1]))

或带有 collapse

的选项

library(collapse)
tfm(df,geo_num_new = ffirst(geo_num,g = cust_id,TRA = "replace"))
  geo_num cust_id sales geo_num_new
1      11       A     2          11
2      12       A     3          11
3      22       B     2          22
4      41       C     1          41
5      42       C     2          41
6      43       C     4          41
7      77       D     6          77
8      71       D     3          77

dplyr 根据某些条件创建新列

cooperboss 回答：dplyr 根据某些条件创建新列

大家都在问