I have a predefined list containing a list of items as below:
group_1<-c("A","B","C")
group_2<-c("D","E","F")
item<-c("A","B","C","D","E","F")
item_price<-(1:6)
df<-data.frame(item,item_price)
> df
item item_price
1 A 1
2 B 2
3 C 3
4 D 4
5 E 5
6 F 6
And now, what I would like to do is to create a new column, multiplying item_price by an arbitrary number, in this case, for items in group_1, item_price will be multiplied by 0.1 and 0.2 for those in group 2. Desired output as below:
> df
item item_price df_new_rate
1 A 1 0.1
2 B 2 0.2
3 C 3 0.3
4 D 4 0.8
5 E 5 1.0
6 F 6 1.2
Since I will need to loop thru item column and see which group different item belongs to, do I need to write a for loop here? Or if there is a short and clear cut way to do so? All ideas are appreciated.
You can use ifelse or case_when if you have more than 2 groups:
library(dplyr)
df %>%
mutate(df_new_rate = case_when(item %in% group_1 ~ 0.1,
item %in% group_2 ~ 0.2,
.default = 0) * item_price)
#> item item_price df_new_rate
#> 1 A 1 0.1
#> 2 B 2 0.2
#> 3 C 3 0.3
#> 4 D 4 0.8
#> 5 E 5 1.0
#> 6 F 6 1.2