如何计算R中的折扣?

Question

我有一个像这样的数据集，它显示了每个产品的价格:

df <- tribble(
~product_id, ~price,  
'123',        35,                
'445',        98, 
'654',        194, 
'135',        2000, 
'156',         10, 
)

我现在想根据以下条件对产品价格进行折扣，公式为:价格*(100 -贴现率)/100

如果价格为X，则在价格上给予Y%的折扣

• <10$: 3%
• 10 - 20美元:5%
• 20 - 30美元:7%
• 30 - 90美元:10%
• 90 - 190: 20%
• 190 - 2000: 30%
• 高于2000$:50%

因此，期望的输出将是这样的:

df <- tribble(
~product_id, ~price,  ~discount_rate,  ~final_price, 
'123',        35,         10,             31.5,
'445',        98,         20,             78.4,
'654',        194,        30,             135.8,
'135',        2000,       50,             1000,
'156',        10,          5,             9.5,
)

我该怎么做?

Answer 1

用cut创建一个'discount_rate'列，然后从折扣价格中减去'price'

library(dplyr)
df <- df %>% 
mutate(discount_rate = as.integer(as.character(cut(price, 
breaks = c(-Inf, 10, 20, 30, 90, 190, 2000, Inf), 
labels = c(3, 5, 7, 10, 20, 30, 50), right = FALSE))),
final_price = price - (price * discount_rate/100))

与产出

# A tibble: 5 × 4
product_id price discount_rate final_price
<chr>      <dbl>         <int>       <dbl>
1 123           35            10        31.5
2 445           98            20        78.4
3 654          194            30       136. 
4 135         2000            50      1000  
5 156           10             5         9.5

Answer 2

您可以创建一个折扣表。

library(fuzzyjoin)
library(dplyr)
discount_table <- data.frame(start = c(0, 10, 20, 30, 90, 190, 2000), 
end =   c(10, 20, 30, 90, 190, 2000, Inf), 
discount = c(0.03, 0.05, 0.07, 0.1, 0.2, 0.3, 0.5))
discount_table
#  start  end discount
#1     0   10     0.03
#2    10   20     0.05
#3    20   30     0.07
#4    30   90     0.10
#5    90  190     0.20
#6   190 2000     0.30
#7  2000  Inf     0.50

用fuzzyjoin与df结合，计算新的价格

fuzzy_left_join(df, discount_table, by = c('price' = 'start', 'price' = 'end'), 
match_fun = c(`>=`, `<`)) %>%
mutate(final_price = price - (price * discount), 
discount = discount * 100)
#  product_id price start   end discount final_price
#  <chr>      <dbl> <dbl> <dbl>    <dbl>       <dbl>
#1 123           35    30    90       10        31.5
#2 445           98    90   190       20        78.4
#3 654          194   190  2000       30       136. 
#4 135         2000  2000   Inf       50      1000  
#5 156           10    10    20        5         9.5

Answer 3

case_when解决方案:

library(tidyverse)
discount <- tribble(
~product_id, ~price,  
'123',        35,                
'445',        98, 
'654',        194, 
'135',        2000, 
'156',         10, 
)
discount %>% 
mutate(discount_rate = case_when(
price < 10 ~ 0.03,
(price >= 10 & price < 20) ~ 5,
(price >= 20 & price < 30) ~ 7,
(price >= 30 & price < 90) ~ 10,
(price >= 90 & price < 190) ~ 20,
(price >= 190 & price < 2000) ~ 30,
price >= 2000 ~ 50),
final_price = (price * (100 - discount_rate)) / 100
)
#> # A tibble: 5 × 4
#>   product_id price discount_rate final_price
#>   <chr>      <dbl>         <dbl>       <dbl>
#> 1 123           35            10        31.5
#> 2 445           98            20        78.4
#> 3 654          194            30       136. 
#> 4 135         2000            50      1000  
#> 5 156           10             5         9.5

^{由reprex包(v2.0.1)在2018-10-29上创建}