//@version=4
// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/

// Linear Regression Slope Annualized with R-squared Histogram
// by SparkyFlary

study(title="Linear Regression Slope Annualized with R-squared Histogram", shorttitle="Linear Regression Slope", overlay=false)

length = input(80, title="Slope length")
rSquaredThreshold = input(0.0, title="R-squared threshold", minval=0, maxval=1)
withAnnualize = input(true, title="Annualize slope?")
daysInYear = input(240, title="Number of bars in a year(if slope is annualized)")
src = input(close, title="Source")
slopeCalcMethod = input("wma-sma", options=["wma-sma", "(linreg-linreg[length])/length"])

nlPrice = log(src)
slope = slopeCalcMethod=="wma-sma" ? 6*(wma(nlPrice, length) - sma(nlPrice, length))/(length-1) : (linreg(nlPrice,length,0)-linreg(nlPrice,length,0)[length])/length
rSquared = pow(correlation(cum(1), nlPrice, length), 2)
slopeAnnualized = (pow(exp(slope),daysInYear)-1) * (rSquared) * 100
mult = withAnnualize ? slopeAnnualized * rSquared : slope * rSquared

trend = rSquared>rSquaredThreshold
rising = mult>mult[1]
falling = mult<mult[1]
up = mult>0
down = mult<0

up_rising_color = color.new(color.green, 0)
up_falling_color = color.new(color.green, 50)
down_falling_color = color.new(color.red, 0)
down_rising_color = color.new(color.red, 50)

c = trend and up and rising?up_rising_color:trend and up and falling?up_falling_color:trend and down and falling?down_falling_color:trend and down and rising?down_rising_color : color.gray

plot(mult, title="Annualized slope x R-squared", style=plot.style_histogram, color = c, linewidth=3)