I have a Deedle series with election data like:

```
"Party A", 304
"Party B", 25
"Party C", 570
....
"Party Y", 2
"Party Z", 258
```

I'd like to create a new series like this:

```
"Party C", 570
"Party A", 304
"Party Z", 258
"Others", 145
```

So I want to take the top 3 as they are and sum all others as a new row. What is the best way to do this?

# Best How To :

I don't think we have anything in Deedle that would make this a one-liner (how disappointing...). So the best I could think of is to get the keys for the top 3 parties and then use `Series.groupInto`

with a key selector that returns either the party name (for the top 3) or returns "Other" (for the other parties):

```
// Sample data set with a bunch of parties
let election =
[ "Party A", 304
"Party B", 25
"Party C", 570
"Party Y", 2
"Party Z", 258 ]
|> series
// Sort the data by -1 times the value (descending)
let byVotes = election |> Series.sortBy (~-)
// Create a set with top 3 keys (for efficient lookup)
let top3 = byVotes |> Series.take 3 |> Series.keys |> set
// Group the series using key selector that tries to find the party in top3
// and using an aggregation function that sums the values (for one or multiple values)
byVotes |> Series.groupInto
(fun k v -> if top3.Contains(k) then k else "Other")
(fun k s -> s |> Series.mapValues float |> Stats.sum)
```