FuturesVsSpot

//Futures vs Spot

study(title = "FuturesVsSpot", shorttitle = "FuturesVsSpot")

len=input(5, minval=1)

usdcny = security("FX_IDC:USDCNY",period, close)

okhigh = security("OKCOIN:BTCUSD1W",period, high*usdcny)
oklow = security("OKCOIN:BTCUSD1W",period, low*usdcny)
okclose =security("OKCOIN:BTCUSD1W",period, close*usdcny)
okcny = security("OKCOIN:BTCCNY",period,close)

huobi = security("HUOBI:BTCCNY",period,close)

ratio = (okclose/okcny)-1
ratioema = ema(ratio,len)

col = ratio<0 ? red : ratio>0 ? green : gray

hline(0,title="0")
plot(ratio, style=histogram,linewidth=1,color=col)
plot(ratioema,style=line,linewidth=1,color=col)
bgcolor(color=col,transp=95)