ZoneBars

//Bill Williams Zone and Squat Bars.  See New Trading Dimensions by Bill Williams, PhD.
//Bars are green (green zone) when the Awesome Oscillator and Accelerater/Decelerator are both positive.
//Bars are red (red zone) when the Awesome Oscillator and Accelerater/Decelerator are both negative.
//Bars are blue when a squat bar is formed, these indicate a battle between bulls and bears and often happen near trend continuation or trend changes.
//Caution: Assumes chart is a bar chart - not a candle chart.
//Caution: Squat bars are accurate only with official exchange volume data - BATS data will give false squat bars.
study(title="ZoneBars", overlay = true)
ao = sma(hl2,5) - sma(hl2,34)
ac = ao - sma( ao, 5 )
isGreen() => ao > ao[1] and ac > ac[1]
isRed() => ao < ao[1] and ac < ac[1]
mfi = (high-low)/volume
rm = roc(mfi,1)
rv = roc(volume,1)
isSquat() => rm < rm[1] and rv > rv[1] 
barcolor(isSquat() ? blue : isGreen() ? green : isRed() ? red : black)