Hi,
I want to rank a list of numbers: 1 2 3 4 5 3 3 3
In kdb+/q, by using rank function, the result is 0 1 2 6 7 3 4 5. The duplicates do not get the same ranking results.
Ideally, I want to have: 0 1 3.5 6 7 3.5 3.5 3.5
Any help would be greatly appreciated!
Thanks,
Kelly
You can use the fby function, e.g.
q)l: 1 2 3 4 5 3 3 3
q)(avg;rank l) fby l
0 1 3.5 6 7 3.5 3.5 3.5
James
Excellent! It works well. Many thanks James!
Just a follow up question…
What if the data is in a table. Say:
t:(a: 1 2 3 4 5 3 3 3)
How can I update ranks:… from t?
Thanks,
Kelly
q)update a,ranks:(avg;rank a) fby a from t
a ranks
-------
1 0
2 1
3 3.5
4 6
5 7
3 3.5
3 3.5
3 3.5
Or you could create a function, say rankp:
q)rankp:{(avg;rank x) fby x}
q)select a,ranks:rankp[a] from t
a ranks
-------
1 0
2 1
3 3.5
4 6
5 7
3 3.5
3 3.5
3 3.5
update rnk:avg rank a by a from t
or
update rnk:(avg;rank a)fby a from t