how to calculate a buy/sell volume of a stock/future

[tiger2014]

I want to know how to calculate a buy/sell volume of a stock/future.

If we can calculate, we can decide how to do it easily.

Thanks.

[DaveSkender]

I'm not familiar with that technique, can you provide more explanation?

[tiger2014]

I have found out how to calculate it, we can use internal bars:

switch

    `close> open => upVol += volume ` 
    `close < open => dnVol -= volume`  
    
    `close > nz(close[1]) => upVol += volume`  
    `close < nz(close[1]) => dnVol -= volume ` 
   
    `nz(upVol[1]) > 0 => upVol += volume ` 
    `nz(dnVol[1]) < 0 => dnVol -= volume  `

[DaveSkender]

This looks like an up/down split version of On-balance Volume (OBV)
Do you have any reputable author references or common name for this indicator?
I'm curious to see if this is just extra info we can add to OBV output or as a new indicator.

[tiger2014]

I got it from this link: https://www.tradingview.com/chart/?solution=43000672561

[DaveSkender]

Maybe Gregory Morris is an authoritative source for these up/down family of indicators, but maybe also Sherman and Marian McClellan