TDIGEST.REVRANK

Syntax
TDIGEST.REVRANK key value [value ...]
Available in:
Redis Stack / Bloom 2.4.0
Time complexity:
O(1)

Returns, for each input value (floating-point), the estimated reverse rank of the value (the number of observations in the sketch that are larger than the value + half the number of observations that are equal to the value).

Multiple reverse ranks can be retrieved in a signle call.

Required arguments

key is key name for an existing t-digest sketch.
value is input value for which the reverse rank should be estimated.

Return value

Array reply - an array of integers populated with revrank_1, revrank_2, ..., revrank_V:

  • -1 - when value is larger than the value of the largest observation.
  • The number of observations - when value is smaller than the value of the smallest observation.
  • Otherwise: an estimation of the number of (observations larger than value + half the observations equal to value).

0 is the reverse rank of the value of the largest observation.

n-1 is the reverse rank of the value of the smallest observation; n denotes the number of observations added to the sketch.

All values are -2 if the sketch is empty.

Examples

redis> TDIGEST.CREATE s COMPRESSION 1000
OK
redis> TDIGEST.ADD s 10 20 30 40 50 60
OK
redis> TDIGEST.RANK s 0 10 20 30 40 50 60 70
1) (integer) -1
2) (integer) 0
3) (integer) 1
4) (integer) 2
5) (integer) 3
6) (integer) 4
7) (integer) 5
8) (integer) 6
redis> TDIGEST.REVRANK s 0 10 20 30 40 50 60 70
1) (integer) 6
2) (integer) 5
3) (integer) 4
4) (integer) 3
5) (integer) 2
6) (integer) 1
7) (integer) 0
8) (integer) -1
redis> TDIGEST.CREATE s COMPRESSION 1000
OK
redis> TDIGEST.ADD s 10 10 10 10 20 20
OK
redis> TDIGEST.RANK s 10 20
1) (integer) 2
2) (integer) 5
redis> TDIGEST.REVRANK s 10 20
1) (integer) 4
2) (integer) 1

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