I would like to know how to calculate the P/E ratio by industry. In this website: http://in.reuters.com/finance/stocks/overview?symbol=DTV.O&exchange=XXCX

It displays the P/E ratio for the current stock, the industry and the sector:

FINANCIALS
             DTV.O  Industry    Sector
P/E (TTM):   12.84   38.88   15.37
EPS (TTM):   4.81    --  --
ROI:         19.26   22.72   15.30
ROE:         --      23.20   18.69

So anyone knows the formula ? My problem is that I have historical data about P/E by stock, and I need to calculate the P/E radio by industry.

Thanks

I would like to know how to calculate the P/E ratio by industry. On this website, it displays the P/E ratio for the current stock, the industry and the sector:

FINANCIALS
             DTV.O  Industry    Sector
P/E (TTM):   12.84   38.88   15.37
EPS (TTM):   4.81    --  --
ROI:         19.26   22.72   15.30
ROE:         --      23.20   18.69

Does anyone know the formula ? My problem is that I have historical data about P/E by stock, and I need to calculate the P/E radio by industry.