S&P 500 Earnings Yield Spread
// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © alexjnelson

//@version=4
study("S&P 500 Yield Spread")

overbought = input(3.16, "Overbought Level")
oversold = input(-3.97, "Oversold Level")

// Color Coding - Credit to The_Caretaker; this spectrum was adapted from his Bollinger Bands Width Percentile indicator

max_val = input(4.44, "Max Expected Value", tooltip="By default this is the maximum since 1960 as of Feb 2 2022 (4.44%)")
min_val = input(-5.82, "Max Expected Value", tooltip="By default this is the minimum since 1960 as of Feb 2 2022 (-5.82%)")

color_type   = input ( "Spectrum",       "Color Type",   input.string,  options = [ "Spectrum", "Solid" ],           inline = "1",   group = "BBWP Plot Settings" )
spec_type  = input ( "Blue Green Red", "Spectrum",     input.string,  options = [ "Blue Red", "Blue Green Red"],   inline = "1",   group = "BBWP Plot Settings" )
is_solid   = input ( #FFFF00,          "Solid",        input.color,                                                inline = "1",   group = "BBWP Plot Settings" )


var c_prcntSpctrm1 = array.new_color ( na )
if barstate.isfirst
    array.push ( c_prcntSpctrm1, #0000FF ),
    array.push ( c_prcntSpctrm1, #000AFF ), array.push ( c_prcntSpctrm1, #0014FF ), array.push ( c_prcntSpctrm1, #001FFF ), array.push ( c_prcntSpctrm1, #0029FF ), array.push ( c_prcntSpctrm1, #0033FF ),
    array.push ( c_prcntSpctrm1, #003DFF ), array.push ( c_prcntSpctrm1, #0047FF ), array.push ( c_prcntSpctrm1, #0052FF ), array.push ( c_prcntSpctrm1, #005CFF ), array.push ( c_prcntSpctrm1, #0066FF ),
    array.push ( c_prcntSpctrm1, #0070FF ), array.push ( c_prcntSpctrm1, #007AFF ), array.push ( c_prcntSpctrm1, #0085FF ), array.push ( c_prcntSpctrm1, #008FFF ), array.push ( c_prcntSpctrm1, #0099FF ), 
    array.push ( c_prcntSpctrm1, #00A3FF ), array.push ( c_prcntSpctrm1, #00ADFF ), array.push ( c_prcntSpctrm1, #00B8FF ), array.push ( c_prcntSpctrm1, #00C2FF ), array.push ( c_prcntSpctrm1, #00CCFF ), 
    array.push ( c_prcntSpctrm1, #00D6FF ), array.push ( c_prcntSpctrm1, #00E0FF ), array.push ( c_prcntSpctrm1, #00EBFF ), array.push ( c_prcntSpctrm1, #00F5FF ), array.push ( c_prcntSpctrm1, #00FFFF ), 
    array.push ( c_prcntSpctrm1, #00FFF5 ), array.push ( c_prcntSpctrm1, #00FFEB ), array.push ( c_prcntSpctrm1, #00FFE0 ), array.push ( c_prcntSpctrm1, #00FFD6 ), array.push ( c_prcntSpctrm1, #00FFCC ), 
    array.push ( c_prcntSpctrm1, #00FFC2 ), array.push ( c_prcntSpctrm1, #00FFB8 ), array.push ( c_prcntSpctrm1, #00FFAD ), array.push ( c_prcntSpctrm1, #00FFA3 ), array.push ( c_prcntSpctrm1, #00FF99 ), 
    array.push ( c_prcntSpctrm1, #00FF8F ), array.push ( c_prcntSpctrm1, #00FF85 ), array.push ( c_prcntSpctrm1, #00FF7A ), array.push ( c_prcntSpctrm1, #00FF70 ), array.push ( c_prcntSpctrm1, #00FF66 ), 
    array.push ( c_prcntSpctrm1, #00FF5C ), array.push ( c_prcntSpctrm1, #00FF52 ), array.push ( c_prcntSpctrm1, #00FF47 ), array.push ( c_prcntSpctrm1, #00FF3D ), array.push ( c_prcntSpctrm1, #00FF33 ), 
    array.push ( c_prcntSpctrm1, #00FF29 ), array.push ( c_prcntSpctrm1, #00FF1F ), array.push ( c_prcntSpctrm1, #00FF14 ), array.push ( c_prcntSpctrm1, #00FF0A ), array.push ( c_prcntSpctrm1, #00FF00 ), 
    array.push ( c_prcntSpctrm1, #0AFF00 ), array.push ( c_prcntSpctrm1, #14FF00 ), array.push ( c_prcntSpctrm1, #1FFF00 ), array.push ( c_prcntSpctrm1, #29FF00 ), array.push ( c_prcntSpctrm1, #33FF00 ), 
    array.push ( c_prcntSpctrm1, #3DFF00 ), array.push ( c_prcntSpctrm1, #47FF00 ), array.push ( c_prcntSpctrm1, #52FF00 ), array.push ( c_prcntSpctrm1, #5CFF00 ), array.push ( c_prcntSpctrm1, #66FF00 ), 
    array.push ( c_prcntSpctrm1, #70FF00 ), array.push ( c_prcntSpctrm1, #7AFF00 ), array.push ( c_prcntSpctrm1, #85FF00 ), array.push ( c_prcntSpctrm1, #8FFF00 ), array.push ( c_prcntSpctrm1, #99FF00 ), 
    array.push ( c_prcntSpctrm1, #A3FF00 ), array.push ( c_prcntSpctrm1, #ADFF00 ), array.push ( c_prcntSpctrm1, #B8FF00 ), array.push ( c_prcntSpctrm1, #C2FF00 ), array.push ( c_prcntSpctrm1, #CCFF00 ), 
    array.push ( c_prcntSpctrm1, #D6FF00 ), array.push ( c_prcntSpctrm1, #E0FF00 ), array.push ( c_prcntSpctrm1, #EBFF00 ), array.push ( c_prcntSpctrm1, #F5FF00 ), array.push ( c_prcntSpctrm1, #FFFF00 ), 
    array.push ( c_prcntSpctrm1, #FFF500 ), array.push ( c_prcntSpctrm1, #FFEB00 ), array.push ( c_prcntSpctrm1, #FFE000 ), array.push ( c_prcntSpctrm1, #FFD600 ), array.push ( c_prcntSpctrm1, #FFCC00 ), 
    array.push ( c_prcntSpctrm1, #FFC200 ), array.push ( c_prcntSpctrm1, #FFB800 ), array.push ( c_prcntSpctrm1, #FFAD00 ), array.push ( c_prcntSpctrm1, #FFA300 ), array.push ( c_prcntSpctrm1, #FF9900 ), 
    array.push ( c_prcntSpctrm1, #FF8F00 ), array.push ( c_prcntSpctrm1, #FF8500 ), array.push ( c_prcntSpctrm1, #FF7A00 ), array.push ( c_prcntSpctrm1, #FF7000 ), array.push ( c_prcntSpctrm1, #FF6600 ), 
    array.push ( c_prcntSpctrm1, #FF5C00 ), array.push ( c_prcntSpctrm1, #FF5200 ), array.push ( c_prcntSpctrm1, #FF4700 ), array.push ( c_prcntSpctrm1, #FF3D00 ), array.push ( c_prcntSpctrm1, #FF3300 ), 
    array.push ( c_prcntSpctrm1, #FF2900 ), array.push ( c_prcntSpctrm1, #FF1F00 ), array.push ( c_prcntSpctrm1, #FF1400 ), array.push ( c_prcntSpctrm1, #FF0000 ), array.push ( c_prcntSpctrm1, #FF0000 )

var c_prcntSpctrm2 = array.new_color ( na )
if barstate.isfirst
    array.push ( c_prcntSpctrm2, #0000FF ),
    array.push ( c_prcntSpctrm2, #0200FC ), array.push ( c_prcntSpctrm2, #0500F9 ), array.push ( c_prcntSpctrm2, #0700F7 ), array.push ( c_prcntSpctrm2, #0A00F4 ), array.push ( c_prcntSpctrm2, #0C00F2 ), 
    array.push ( c_prcntSpctrm2, #0F00EF ), array.push ( c_prcntSpctrm2, #1100ED ), array.push ( c_prcntSpctrm2, #1400EA ), array.push ( c_prcntSpctrm2, #1600E8 ), array.push ( c_prcntSpctrm2, #1900E5 ), 
    array.push ( c_prcntSpctrm2, #1C00E2 ), array.push ( c_prcntSpctrm2, #1E00E0 ), array.push ( c_prcntSpctrm2, #2100DD ), array.push ( c_prcntSpctrm2, #2300DB ), array.push ( c_prcntSpctrm2, #2600D8 ),
    array.push ( c_prcntSpctrm2, #2800D6 ), array.push ( c_prcntSpctrm2, #2B00D3 ), array.push ( c_prcntSpctrm2, #2D00D1 ), array.push ( c_prcntSpctrm2, #3000CE ), array.push ( c_prcntSpctrm2, #3300CC ),
    array.push ( c_prcntSpctrm2, #3500C9 ), array.push ( c_prcntSpctrm2, #3800C6 ), array.push ( c_prcntSpctrm2, #3A00C4 ), array.push ( c_prcntSpctrm2, #3D00C1 ), array.push ( c_prcntSpctrm2, #3F00BF ), 
    array.push ( c_prcntSpctrm2, #4200BC ), array.push ( c_prcntSpctrm2, #4400BA ), array.push ( c_prcntSpctrm2, #4700B7 ), array.push ( c_prcntSpctrm2, #4900B5 ), array.push ( c_prcntSpctrm2, #4C00B2 ),
    array.push ( c_prcntSpctrm2, #4F00AF ), array.push ( c_prcntSpctrm2, #5100AD ), array.push ( c_prcntSpctrm2, #5400AA ), array.push ( c_prcntSpctrm2, #5600A8 ), array.push ( c_prcntSpctrm2, #5900A5 ), 
    array.push ( c_prcntSpctrm2, #5B00A3 ), array.push ( c_prcntSpctrm2, #5E00A0 ), array.push ( c_prcntSpctrm2, #60009E ), array.push ( c_prcntSpctrm2, #63009B ), array.push ( c_prcntSpctrm2, #660099 ),
    array.push ( c_prcntSpctrm2, #680096 ), array.push ( c_prcntSpctrm2, #6B0093 ), array.push ( c_prcntSpctrm2, #6D0091 ), array.push ( c_prcntSpctrm2, #70008E ), array.push ( c_prcntSpctrm2, #72008C ), 
    array.push ( c_prcntSpctrm2, #750089 ), array.push ( c_prcntSpctrm2, #770087 ), array.push ( c_prcntSpctrm2, #7A0084 ), array.push ( c_prcntSpctrm2, #7C0082 ), array.push ( c_prcntSpctrm2, #7F007F ),
    array.push ( c_prcntSpctrm2, #82007C ), array.push ( c_prcntSpctrm2, #84007A ), array.push ( c_prcntSpctrm2, #870077 ), array.push ( c_prcntSpctrm2, #890075 ), array.push ( c_prcntSpctrm2, #8C0072 ), 
    array.push ( c_prcntSpctrm2, #8E0070 ), array.push ( c_prcntSpctrm2, #91006D ), array.push ( c_prcntSpctrm2, #93006B ), array.push ( c_prcntSpctrm2, #960068 ), array.push ( c_prcntSpctrm2, #990066 ),
    array.push ( c_prcntSpctrm2, #9B0063 ), array.push ( c_prcntSpctrm2, #9E0060 ), array.push ( c_prcntSpctrm2, #A0005E ), array.push ( c_prcntSpctrm2, #A3005B ), array.push ( c_prcntSpctrm2, #A50059 ), 
    array.push ( c_prcntSpctrm2, #A80056 ), array.push ( c_prcntSpctrm2, #AA0054 ), array.push ( c_prcntSpctrm2, #AD0051 ), array.push ( c_prcntSpctrm2, #AF004F ), array.push ( c_prcntSpctrm2, #B2004C ), 
    array.push ( c_prcntSpctrm2, #B50049 ), array.push ( c_prcntSpctrm2, #B70047 ), array.push ( c_prcntSpctrm2, #BA0044 ), array.push ( c_prcntSpctrm2, #BC0042 ), array.push ( c_prcntSpctrm2, #BF003F ), 
    array.push ( c_prcntSpctrm2, #C1003D ), array.push ( c_prcntSpctrm2, #C4003A ), array.push ( c_prcntSpctrm2, #C60038 ), array.push ( c_prcntSpctrm2, #C90035 ), array.push ( c_prcntSpctrm2, #CC0033 ),
    array.push ( c_prcntSpctrm2, #CE0030 ), array.push ( c_prcntSpctrm2, #D1002D ), array.push ( c_prcntSpctrm2, #D3002B ), array.push ( c_prcntSpctrm2, #D60028 ), array.push ( c_prcntSpctrm2, #D80026 ), 
    array.push ( c_prcntSpctrm2, #DB0023 ), array.push ( c_prcntSpctrm2, #DD0021 ), array.push ( c_prcntSpctrm2, #E0001E ), array.push ( c_prcntSpctrm2, #E2001C ), array.push ( c_prcntSpctrm2, #E50019 ),
    array.push ( c_prcntSpctrm2, #E80016 ), array.push ( c_prcntSpctrm2, #EA0014 ), array.push ( c_prcntSpctrm2, #ED0011 ), array.push ( c_prcntSpctrm2, #EF000F ), array.push ( c_prcntSpctrm2, #F2000C ), 
    array.push ( c_prcntSpctrm2, #F4000A ), array.push ( c_prcntSpctrm2, #F70007 ), array.push ( c_prcntSpctrm2, #F90005 ), array.push ( c_prcntSpctrm2, #FC0002 ), array.push ( c_prcntSpctrm2, #FF0000 )

f_clrSlct ( percent, select, type, solid, array1, array2 ) => select == "Solid" ? solid : array.get ( type == "Blue Green Red" ? array1 : array2, round ( percent ) )

// get the % distance between the max and min val, but ensure that a number is not being used beyond the min or max
get_pct (val) => 100 * (min(max(val, min_val), max_val) - min_val) / (max_val - min_val)

// actual code
treasury_10y = security("US10Y", "M", close)
sp500_earnings = security("QUANDL:MULTPL/SP500_EARNINGS_YIELD_MONTH", "M", close)
spread = treasury_10y - sp500_earnings

color_spec = f_clrSlct ( get_pct(spread), color_type, spec_type, is_solid, c_prcntSpctrm1, c_prcntSpctrm2 )

plot(spread, color=color_spec)
hline(overbought, color=color.red, title="Overbought")
hline(oversold, color=color.green, title="Oversold")