How create a pine script that places buy/sell signals on chart when the MFI is above 50 AND the DMI+ crosses the DMI-

Question

I have no idea what I am doing and the idea seems simple to code, but I have no experience doing this.

Answer 1

Morning Brad Standige,

Please see below. Does this answer you question:

//@version=4
study("StackOverFlow", shorttitle="SOF", overlay=false, format=format.price)

//////////////////// Money Flow Index Start

// Input
mfi_period = input(14, title="MFI Period", minval=1)
mfi_upper = input(80, title="Upper Treshold Line", minval=1)
mfi_middle = input(50, title="Upper Treshold Line", minval=1)
mfi_lower = input(20, title="Lower Treshold Line", minval=1)


// Calculates the money flow index value. 
calc_mfi(len) =>
    tp = nz(hlc3)  // typical price
    pos_mf = sum(change(tp) > 0 ? tp : 0, len) * volume // pos. money flow
    neg_mf = sum(change(tp) < 0 ? tp : 0, len) * volume // neg. money flow
    mr = pos_mf / neg_mf // money ratio
    mfi = 100 - (100 / (1 + mr))
    mfi

mfi_val = calc_mfi(mfi_period)


// Drawings
plot(mfi_val, title="MFI", color=color.teal, linewidth=2)
plotshape(mfi_val, style=shape.labeldown, location=location.absolute, color=color.teal,  textcolor=color.white, show_last=1, text="MFI", transp=0, title="MFI")

hline(mfi_upper, title="Upper Treshold", color=color.gray, linestyle=hline.style_dotted, linewidth=2)
hline(mfi_middle, title="Middle Treshold", color=color.gray, linestyle=hline.style_dotted, linewidth=2)
hline(mfi_lower, title="Lower Treshold", color=color.gray, linestyle=hline.style_dotted, linewidth=2)

//////////////////// Money Flow Index Finish

//////////////////// DMI Start

// Input
len = input(title="Length", type=input.integer, defval=14)
th = input(title="Threshold", type=input.integer, defval=20)

// Calculates DMI value. 
TrueRange = max(max(high - low, abs(high - nz(close[1]))), abs(low - nz(close[1])))
DirectionalMovementPlus = high - nz(high[1]) > nz(low[1]) - low ? max(high - nz(high[1]), 0) : 0
DirectionalMovementMinus = nz(low[1]) - low > high - nz(high[1]) ? max(nz(low[1]) - low, 0) : 0

SmoothedTrueRange = 0.0
SmoothedTrueRange := nz(SmoothedTrueRange[1]) - nz(SmoothedTrueRange[1]) / len + TrueRange
SmoothedDirectionalMovementPlus = 0.0
SmoothedDirectionalMovementPlus := nz(SmoothedDirectionalMovementPlus[1]) - 
   nz(SmoothedDirectionalMovementPlus[1]) / len + DirectionalMovementPlus
SmoothedDirectionalMovementMinus = 0.0
SmoothedDirectionalMovementMinus := nz(SmoothedDirectionalMovementMinus[1]) - 
   nz(SmoothedDirectionalMovementMinus[1]) / len + DirectionalMovementMinus

DIPlus = SmoothedDirectionalMovementPlus / SmoothedTrueRange * 100
DIMinus = SmoothedDirectionalMovementMinus / SmoothedTrueRange * 100

// Drawings
plot(DIPlus, color=color.green, title="DI+", transp=0)
plotshape(DIPlus, style=shape.labeldown, location=location.absolute, color=color.green,  textcolor=color.white, show_last=1, text="DIPlus", transp=0, title="DIPlus")

plot(DIMinus, color=color.red, title="DI-", transp=0)
plotshape(DIMinus, style=shape.labeldown, location=location.absolute, color=color.red,  textcolor=color.white, show_last=1, text="DIMinus", transp=0, title="DIMinus")



// Visual Alerts
buy = (DIPlus > DIMinus) and mfi_val > 50
sell = (DIMinus > DIPlus) and mfi_val > 50

plotshape(buy==1? buy : na, title="ADX Up", style=shape.square,location=location.top, color=color.green, transp=0, size=size.tiny)
plotshape(sell==1? sell : na, title="ADX Down", style=shape.square,location=location.bottom, color=color.red, transp=0, size=size.tiny)

// Condition Alerts
alertcondition(buy==1 ? buy : na, title="Buy Alert", message="Buy, {{close}}")
alertcondition(sell==1 ? sell :na, title="Sell Alert", message="Sell, {{close}}")

//////////////////// DMI Finish

Answer 2

I am quite a beginner on Pine script but I think the MFI is a built-in function and you don't need to have the details of the computation. This works in pine version 5.

//MFI computation

mfi_period = input(title="MFI Period", defval=14)
src = hlc3   
mf = ta.mfi(src, mfi_period)

//Plot
overbought=hline(80, title="Overbought", color=#787B86)
oversold=hline(20, title="Oversold", color=#787B86)
plot(mf, "MF", color=#7E57C2)

Details on TradingView Pine manual for MFI function