Agregue una nueva fila sobre la base de los valores de columna en R

A continuación se muestra una solución:

df <- data.frame(
  Consumer = c(rep(43, 5), rep(41, 5)),
  Product = rep(sample(100:900,size = 5, replace = F), 2),
  Firm = c(sample(rep(0:1, 5), replace = T)),
  Juicy = c(sample(rep(0:1, 5), replace = T)),
  Sweet = c(sample(rep(0:1, 5), replace = T)),
  Ideal_Firm = 1, 
  Ideal_Juicy = c(rep(1, 5), rep(2, 5)), 
  Ideal_Sweet = c(rep(1, 5), rep(0, 5))
)

library(dplyr)
df <- merge(
  # Bind the observation...
  df %>% select(Consumer:Sweet) %>% 
    pivot_wider(id_cols = Consumer,names_from = Product,values_from = Firm:Sweet),
  # ... to the ideal
  df %>% group_by(Consumer) %>% 
    # Here I put mean, but it could be 1, median, min, max... If I understood correctly, it has to be 1?
    summarise(across(Ideal_Firm:Ideal_Sweet, ~mean(.x))) %>%
    # Rename so the column name has the form [characteristic]_ideal instead of Ideal_[characteristic]
    # remove prefix Ideal_ ...
    rename_at(.vars = vars(starts_with("Ideal_")),
              .funs = funs(sub("Ideal_", "", .))) %>%
    # ... add _Ideal as a suffix instead
    rename_at(vars(-Consumer), function(x) paste0(x,"_Ideal"))
)

# Then manipulate to get into long form again
df <- df %>% pivot_longer(cols = !Consumer) %>%
  separate(name, c("Characteristic", "Product")) %>%
  pivot_wider(id_cols = Consumer:Product, names_from = Characteristic, values_from = value)
df