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OPEN-SOURCE SCRIPT

Weighted percentile nearest rank

Updated
Yo, posting it for the whole internet, took the whole day to find / to design the actual working solution for weighted percentile 'nearest rank' algorithm, almost no reliable info online and a lot of library-style/textbook-style solutions that don't provide on real world production level.

The principle:

0) initial data
data = 22, 33, 11, 44, 55
weights = 5 , 3 , 2 , 1 , 4

array(s) size = 5

1) sort data array, apply the sorting pattern to the weights array, resulting:
data = 11, 22, 33, 44, 55
weights = 2 , 5 , 3 , 1 , 4

2) get weights cumsum and sum:
weights = 2, 5, 3 , 1 , 4
weights_cum = 2, 7, 10, 11, 15
weights_sum = 15

3) say we wanna find 50th percentile, get a threshold value:
n = 50
thres = weights_sum / 100 * n
7.5 = 15 / 100 * 50

4) iterate through weights_cum until you find a value that >= the threshold:
for i = 0 to size - 1
2 >= 7.5 ? nah
7 >= 7.5 ? nah
10 >= 7.5 ? aye

5) take the iteration index that resulted "aye", and find the data value with the same index, that's gonna be the resulting percentile.
i = 2
data = 33

This one is not an approximation, not an estimator, it's the actual weighted percentile nearest rank as it is.

I tested the thing extensively and it works perfectly.
For the skeptics, check lines 40, 41, 69 in the code, you can comment/uncomment dem to switch for unit (1) weights, resulting in the usual non-weighted percentile nearest rank that ideally matches the TV's built-in function.

Shoutout for @wallneradam for the sorting function mane
...
Live Long and Prosper
Release Notes
Significant Update Alert

- 10x and faster calculation speed due to improved algo complexity from O(n²) to O(n log n), effectively allowing you to comfortably use the thing on long moving windows (as you shoulda anyways) like 256 datapoints and more;
- Now supports combined weighting by time And inferred volume at the same time (as it should've).
nearestpercentilePine utilitiesrankstatisticsweighted

Open-source script

In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in publication is governed by House rules. You can favorite it to use it on a chart.

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