Adding Specific columns values in R-CodePudding

I am trying to add two specific values in R. I am new to R and so far I have used colSums and it does give me the right values. However, I was wondering if there was a way to add specific cells and then add as them as row to the dataframe. In this case, I would like to add the last two columns.

Here's sample data:

col1	col2	col3
3	7	a
2	4	b
1	5	c

Desired output:

col1	col2	col3
3	7	a
3	9	b&c

CodePudding user response：

Admittingly, this is not pretty as it mixes tidyverse and base R. But, we can use a custom function, since we are dealing with columns of different classes, i.e colSums will not work because "a" "b" is not "ab".

library(dplyr)
df <-
  tribble(
    ~col1, ~col2, ~col3,
    3, 7, "a",
    2, 4, "b",
    1, 5, "c"
  )

f <- function(df) {
  replace <- df %>%
    tail(2) %>%
    summarise(
      col1 = sum(col1),
      col2 = sum(col2),
      col3 = paste0(col3, collapse = "&")
    )
  bind_rows(
    df %>% head(-2),
    replace
  )
}

df %>%
  f()
#> # A tibble: 2 x 3
#>    col1  col2 col3 
#>   <dbl> <dbl> <chr>
#> 1     3     7 a    
#> 2     3     9 b&c

CodePudding user response：

DF <- DF %>%
recode(col3, b = "b&c", c = "b&c")
group_by(col3) %
summarise(col1 = sum(col1), col2 = sum(col2)) %
ungroup()