There is dataframe raw_df as below:

library(tidyverse)    
detail <- data.frame(cat=c("a","a","a","b","b","b","b","c","c"),
                         single_amount=c(1,3,7,2,1,4,6,1,6))
    
    total <- data.frame(cat=c("a","b","c"),
                        total_amount=c(20,10,9))
    
    raw_df <- detail %>% left_join(total,by='cat')

I defined self function allocate_data_m to allocate total_amount when cumsum(single_data) is less then total_amount

allocate_data_m <- function(data,single_data,total_data){
 out <- cumsum_single_data <- rep('NA',nrow(data))
  for (grouprow in seq_len(nrow(data))){
    
    cumsum_single_data[grouprow] <- 
      if_else(grouprow ==1,data[grouprow,single_data],
              cumsum_single_data[grouprow-1] + data[grouprow,single_data])
    
     out[grouprow] <- if_else(cumsum_single_data[grouprow] < data[grouprow,total_data],data[grouprow,single_data],0)
  }
    out 
}

when run the allocate_data_m in mutate, the error occur .Anyone can help ? Thanks!

raw_df %>% group_by(cat) %>%
  mutate(amount_x_all = allocate_data_m(cur_data(),single_amount,total_amount))