Sum Product of a list in dataframe by Order id in R-CodePudding

I am doing a project which is similar to Uber Eat. I want to create new column in a data frame to calculate sub-total of these orders but because the class of each column is "list", R is not allowing me to do that. Do you know any ways to do it.

Thank you

a = c(1,2,3)
b = 1:2
c = (3,1)


P1 = c(12,13,4)
P2 = c(2,4)
P3 = c(12,1)

#My given dataframe will be:
Order  | Price   | Sub-total
a      | P1      |   sum(a*P1)
b      | P2      |   sum(b*P2)
c      |  P3     |    sum(c*P3)

Expect output: Subtotal = [50, 10, 37]

Please see the attached image to understand my dataframe My dataframe

My goal is how to compute aP1, bP2, cP3 and then total sum of aP1....

CodePudding user response：

First, store your respective Order and Price data into a list

a = c(1,2,3)
b = 1:2
c = c(3,1)

P1 = c(12,13,4)
P2 = c(2,4)
P3 = c(12,1)

Order <- list(a, b, c)
Price <- list(P1, P2, P3)

Use a tibble so that you can easily set list columns.

Then using the tidyverse structure, map over the two list columns and apply your formula.

library(dplyr)
library(purrr)

df <- tibble(Order = Order, Price = Price)

df <- df %>% 
  mutate(Sub_total = map2_dbl(Order, Price, ~ sum( .x * .y)))

The result will be as you expected. You can see your original data stored as lists and then your sub-totals.

> df
# A tibble: 3 x 3
  Order     Price     Sub_total
  <list>    <list>        <dbl>
1 <dbl [3]> <dbl [3]>        50
2 <int [2]> <dbl [2]>        10
3 <dbl [2]> <dbl [2]>        37

The total sum would then be sum(df$Sub_total) which is 97.

CodePudding user response：

library(tidyverse)

orders <- list(
  a = c(1,2,3),
  b = 1:2,
  c = c(3,1)
)

prices <- list(
  P1 = c(12,13,4),
  P2 = c(2,4),
  P3 = c(12,1)
)

tibble(
  Order = orders,
  Price = prices
) %>%
  mutate(
    sub_total = Order %>% map2_dbl(Price, ~ sum(.x * .y))
  )
#> # A tibble: 3 x 3
#>   Order        Price        sub_total
#>   <named list> <named list>     <dbl>
#> 1 <dbl [3]>    <dbl [3]>           50
#> 2 <int [2]>    <dbl [2]>           10
#> 3 <dbl [2]>    <dbl [2]>           37

^{Created on 2021-10-01 by the reprex package (v2.0.1)}