//@version=4
study(title="Range Filter [DW]", shorttitle="RF [DW]", overlay=true)
//This is an experimental study designed to filter out minor price action for a clearer view of trends.
//Inspired by the QQE's volatility filter, this filter applies the process directly to price rather than to a smoothed RSI.
//First, a smooth average price range is calculated for the basis of the filter and multiplied by a specified amount.
//Next, the filter is calculated by gating price movements that do not exceed the specified range.
//Lastly the target ranges are plotted to display the prices that will trigger filter movement.
//Custom bar colors are included. The color scheme is based on the filtered price trend.
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Updates:
// -> Migrated to v4.
// -> Range Filter and the bands are now calculated in a singular function.
// -> There are now two different calculation methods for the filter. Select the type you want to use via the "Filter Type" input. Type 1 is the original formula.
// -> Multiple range sizing methods are now available. You can choose from the following scales:
// - Points
// - Pips (Works best with forex pairs, obviously)
// - Ticks
// - % of Price
// - ATR
// - Average Change (Default. This is the original sizing method.)
// - Standard Deviation
// - Absolute (Absolute numerical value)
// -> Range smoothing is now optional, and you can specify your smoothing length. Smoothing only affects dynamic scales (ATR, Average Change, and Standard Deviation).
// -> Filter movement can now be determined using wicks or close. This can be specified via the "Movement Source" input.
// -> Stability Fix: Added correction for NaN values to stabilize initial states.
// -> Reorganized the script structure.
// -> Revamped the color scheme.
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Updates:
// - The Range Filter functions have now been rebuilt using Pine's awesome new array functions.
// - Standard deviation calculation has been adjusted to calculate the same as TV's built in stdev() function.
// - Rewritten filter direction and bar color variables.
// - Included an external output variable for trend information that can easily be sent to other scripts without hardcoding.
// The output format is 1 for bullish, and -1 for bearish.
// To use this external variable with another script, simply select it from your other script's source dropdown tab.
// - Added the ability to average range filter values based on a user defined number of filter changes.
// This averaging method utilized the Conditional Sampling EMA function I introduced in my Resampling Filter Pack and only takes a new sample when the filter changes its value.
// This opens up a whole new world of possible filter outputs.
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Functions
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Conditional Sampling EMA Function
Cond_EMA(x, cond, n)=>
var val = array.new_float(0)
var ema_val = array.new_float(1)
if cond
array.push(val, x)
if array.size(val) > 1
array.remove(val, 0)
if na(array.get(ema_val, 0))
array.fill(ema_val, array.get(val, 0))
array.set(ema_val, 0, (array.get(val, 0) - array.get(ema_val, 0))*(2/(n + 1)) + array.get(ema_val, 0))
EMA = array.get(ema_val, 0)
EMA
//Conditional Sampling SMA Function
Cond_SMA(x, cond, n)=>
var vals = array.new_float(0)
if cond
array.push(vals, x)
if array.size(vals) > n
array.remove(vals, 0)
SMA = array.avg(vals)
SMA
//Standard Deviation Function
Stdev(x, n)=>
sqrt(Cond_SMA(pow(x, 2), 1, n) - pow(Cond_SMA(x, 1, n), 2))
//Range Size Function
rng_size(x, scale, qty, n)=>
ATR = Cond_EMA(tr(true), 1, n)
AC = Cond_EMA(abs(x - x[1]), 1, n)
SD = Stdev(x, n)
rng_size = scale=="Pips" ? qty*0.0001 : scale=="Points" ? qty*syminfo.pointvalue : scale=="% of Price" ? close*qty/100 : scale=="ATR" ? qty*ATR :
scale=="Average Change" ? qty*AC : scale=="Standard Deviation" ? qty*SD : scale=="Ticks" ? qty*syminfo.mintick : qty
//Two Type Range Filter Function
rng_filt(h, l, rng_, n, type, smooth, sn, av_rf, av_n)=>
rng_smooth = Cond_EMA(rng_, 1, sn)
r = smooth ? rng_smooth : rng_
var rfilt = array.new_float(2, (h + l)/2)
array.set(rfilt, 1, array.get(rfilt, 0))
if type=="Type 1"
if h - r > array.get(rfilt, 1)
array.set(rfilt, 0, h - r)
if l + r < array.get(rfilt, 1)
array.set(rfilt, 0, l + r)
if type=="Type 2"
if h >= array.get(rfilt, 1) + r
array.set(rfilt, 0, array.get(rfilt, 1) + floor(abs(h - array.get(rfilt, 1))/r)*r)
if l <= array.get(rfilt, 1) - r
array.set(rfilt, 0, array.get(rfilt, 1) - floor(abs(l - array.get(rfilt, 1))/r)*r)
rng_filt1 = array.get(rfilt, 0)
hi_band1 = rng_filt1 + r
lo_band1 = rng_filt1 - r
rng_filt2 = Cond_EMA(rng_filt1, rng_filt1 != rng_filt1[1], av_n)
hi_band2 = Cond_EMA(hi_band1, rng_filt1 != rng_filt1[1], av_n)
lo_band2 = Cond_EMA(lo_band1, rng_filt1 != rng_filt1[1], av_n)
rng_filt = av_rf ? rng_filt2 : rng_filt1
hi_band = av_rf ? hi_band2 : hi_band1
lo_band = av_rf ? lo_band2 : lo_band1
[hi_band, lo_band, rng_filt]
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Inputs
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Filter Type
f_type = input(defval="Type 1", options=["Type 1", "Type 2"], title="Filter Type")
//Movement Source
mov_src = input(defval="Close", options=["Wicks", "Close"], title="Movement Source")
//Range Size Inputs
rng_qty = input(defval=2.618, minval=0.0000001, title="Range Size")
rng_scale = input(defval="Average Change", options=["Points", "Pips", "Ticks", "% of Price", "ATR", "Average Change", "Standard Deviation", "Absolute"], title="Range Scale")
//Range Period
rng_per = input(defval=14, minval=1, title="Range Period (for ATR, Average Change, and Standard Deviation)")
//Range Smoothing Inputs
smooth_range = input(defval=true, title="Smooth Range")
smooth_per = input(defval=27, minval=1, title="Smoothing Period")
//Filter Value Averaging Inputs
av_vals = input(defval=false, title="Average Filter Changes")
av_samples = input(defval=2, minval=1, title="Number Of Changes To Average")
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Definitions
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//High And Low Values
h_val = mov_src=="Wicks" ? high : close
l_val = mov_src=="Wicks" ? low : close
//Range Filter Values
[h_band, l_band, filt] = rng_filt(h_val, l_val, rng_size((h_val + l_val)/2, rng_scale, rng_qty, rng_per), rng_per, f_type, smooth_range, smooth_per, av_vals, av_samples)
//Direction Conditions
var fdir = 0.0
fdir := filt > filt[1] ? 1 : filt < filt[1] ? -1 : fdir
upward = fdir==1 ? 1 : 0
downward = fdir==-1 ? 1 : 0
//Colors
filt_color = upward ? #05ff9b : downward ? #ff0583 : #cccccc
bar_color = upward and (close > filt) ? (close > close[1] ? #05ff9b : #00b36b) :
downward and (close < filt) ? (close < close[1] ? #ff0583 : #b8005d) : #cccccc
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Outputs
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
//Filter Plot
filt_plot = plot(filt, color=filt_color, linewidth=3, transp=0, title="Filter")
//Band Plots
h_band_plot = plot(h_band, color=#05ff9b, transp=100, title="High Band")
l_band_plot = plot(l_band, color=#ff0583, transp=100, title="Low Band")
//Band Fills
fill(h_band_plot, filt_plot, color=#00b36b, transp=85, title="High Band Fill")
fill(l_band_plot, filt_plot, color=#b8005d, transp=85, title="Low Band Fill")
//Bar Color
barcolor(bar_color)
//External Trend Output
plot(fdir, transp=100, editable=false, display=display.none, title="External Output - Trend Signal")
