Sum by aggregating complex paired names in R - r

Question

In R, I'm trying to aggregate a dataframe based on unique IDs, BUT I need to use some kind of wild card value for the IDs. Meaning I have paired names like this:
lion_tiger
elephant_lion
tiger_lion
And I need the lion_tiger and tiger_lion IDs to be summed together, because the order in the pair does not matter.
Using this dataframe as an example:
df <- data.frame(pair = c("1_3","2_4","2_2","1_2","2_1","4_2","3_1","4_3","3_2"),
value = c("12","10","19","2","34","29","13","3","14"))
So the values for pair IDs, "1_2" and "2_1" need to be summed in a new table. That new row would then read:
1_2 36
Any suggestions? While my example has numbers as the pair IDs, in reality I would need this to read in text (like the lion_tiger" example above).

Answer 1

We can split the 'pair' column by _, then sort and paste it back, use it in a group by function to get the sum
tapply(as.numeric(as.character(df$value)),
sapply(strsplit(as.character(df$pair), '_'), function(x)
paste(sort(as.numeric(x)), collapse="_")), FUN = sum)
Or another option is gsubfn
library(gsubfn)
df$pair <- gsubfn('([0-9]+)_([0-9]+)', ~paste(sort(as.numeric(c(x, y))), collapse='_'),
as.character(df$pair))
df$value <- as.numeric(as.character(df$value))
aggregate(value~pair, df, sum)

Answer 2

Using tidyverse and purrrlyr
df <- data.frame(name=c("lion_tiger","elephant_lion",
"tiger_lion"),value=c(1,2,3),stringsAsFactors=FALSE)
require(tidyverse)
require(purrrlyr)
df %>% separate(col = name, sep = "_", c("A", "B")) %>%
by_row(.collate = "rows",
..f = function(this_row) {
paste0(sort(c(this_row$A, this_row$B)), collapse = "_")
}) %>%
rename(sorted = ".out") %>%
group_by(sorted) %>%
summarize(sum(value))%>%show
## A tibble: 2 x 2
# sorted `sum(value)`
# <chr> <dbl>
#1 elephant_lion 2
#2 lion_tiger 4