Indian Major indices (NIFTY & BANKNIFTY) doesn't have volumes as they are not traded. So we imported volumes from their future current month and use price of spot to calculate VWAP.
For day trading, it is assumed that (a) when price is above VWAP, it shows price has buying pressure (b) when price is below VWAP, it shows price has selling pressure (c) when price is hovering around VWAP, it is assumed, price is in range and forming some sort of pattern for intraday.
One should never trade only based on VWAP but add something else like EMA, SuperTrend for additional confirmation to execute any trade.
PS: This VWAP indicator works well with all symbols which has volume and added additional volume (from futures) on NIFTY & BANKNIFTY SPOT.