CODEWITHSUNDEEP
r
SNT
SNT

Reputation: 1433

Multiply two rows from same dataframe r

I have a dataframe where I want to calculate a new row based on the two existing rows by multiplying them. The structure of my dataframe is as below: 

structure(list(month = c("mazda", "yamaha", "car"), april = c(11, 
12, 0.1), may = c(14, 15, 0.5)), row.names = c(NA, -3L), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"), vars = "month", drop = TRUE, indices = list(
    2L, 0L, 1L), group_sizes = c(1L, 1L, 1L), biggest_group_size = 1L, labels = structure(list(
    month = c("car", "mazda", "yamaha")), row.names = c(NA, -3L
), class = "data.frame", vars = "month", drop = TRUE))

I want to add a row total which would be a product of mazda and car. And if row car is not found it should be 0 in the new row total. Desired output I am trying to achieve :

# A tibble: 4 x 3
# Groups:   month [4]
  month  april   may
  <chr>  <dbl> <dbl>
1 mazda   11    14  
2 yamaha  12    15  
3 car      0.1   0.5
4 total    1.1   7

Upvotes: 0

Views: 460

Answers (1)

Maurits Evers
Maurits Evers

Reputation: 50728

This really sounds/looks like an XY problem. I would advise rethinking your general code & data design. For example, why is column 1 labelled month but then contains entries "mazda", "yamaha", "car" and "total"?

For what it's worth, you can reproduce your expected output with

rbind(df, c(month = "total", df[df$month == "mazda", -1] * df[df$month == "car", -1]))
## A tibble: 4 x 3
## Groups:   month [4]
#  month  april   may
#  <chr>  <dbl> <dbl>
#1 mazda   11    14
#2 yamaha  12    15
#3 car      0.1   0.5
#4 total    1.1   7

Upvotes: 1

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