Display bar count since recent high or low

1. Since you are requesting a solution that works in a custom watchlist column I had to move your question out of the "Chart Studies" topic and into the "Watch Lists" topic.
2. Your description left out a lot of detail. There are many different ways your requests can be interpreted. So I will have to explain the assumptions I was forced to make to help the rest of our viewers understand how to interpret the output of this code.
3. In this case, previous high or low is based on a pivot in price action. A price pivot for this purpose is determined using three bars.
4. For a swing high pivot the price action must make a higher or equal high, followed by a lower high. The counts continue only so long as each successive bar makes a lower or equal high compared to the previous bar. (there is another way to define this but this is how I have written this specific solution)
5. For a swing low pivot the price action must make a lower or equal low, followed by a higher low. The counts continue only so long as each successive bar makes a higher or equal low compared to the previous bar. (there is another way to define this but this is how I have written this specific solution)

So you see there is an awful lot more detail required than you included in your request. And I haven't even covered all of it here because I am running out of time for completing this response.

Here is the code that is used to display these counts in a custom watchlist column. The column can only display one value at a time. So at the bottom of the code I have included two different plot statements. One to display the counts since high and another to display the counts since low. Just move the "#" symbol to select which one to display. You will have to add two custom columns to the watchlist and set each one to a different plot statement.

def oneBarPivotHigh = high[1] >= high[2] and high < high[1];
def oneBarPivotLow = low[1] <= low[2] and low > low[1];
rec countSinceHigh = if oneBarPivotHigh then 1 else if high <= high[1] then countSinceHigh[1] + 1 else 0;
rec countSinceLow = if oneBarPivotLow then 1 else if low >= low[1] then countSinceLow[1] + 1 else 0;
# use this to display the bar count since recent high pivot
plot data = countSinceHigh;
# use thhis to display the bar count since recent low pivot
#plot data = countSinceLow;