Change the Coloring of a Plot Based on a Condition

[Chuck]

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How to change the color of a plot based on a condition that you define. The 'HullMovingAvg' illustrates this very well. Here is its code:

input price = close;
input length = 20;
input displace = 0;

plot HMA = MovingAverage(AverageType.HULL, price, length)[-displace];

HMA.DefineColor("Up", GetColor(1));
HMA.DefineColor("Down", GetColor(0));
HMA.AssignValueColor(if HMA > HMA[1] then HMA.color("Up") else HMA.color("Down"));

In the above HMA>HMA[1] is the condition that says IF the current HMA is greater than the previous value of the HMA, i.e. HMA > HMA[1] , THEN paint the plot with the “Up” color which is defined as color(1) OTHERWISE/ELSEpaint the plot with the “Down” color which is defined as color (2). (1) and (2) are color index numbers. Color-assigned-index-numbers are explained in the separate topic.
The condition is always in a 'if…. then…. else' format. If-statements may be nested without limits. The format thenbecomes 'if…..then….. else if…..then…..else if…..then……else'. The closing 'else' is always present and relates to the initialif…. then when none of the nested if …then’s produce a result.

Example:
if SlowK > SlowD then color.green else if SlowK < SlowD then color.red else color.gray
The multiple conditions may be used to define a conditional statements. They are joined by 'and' or its equivalent '&&'.

Example:
def RangeCondition = ADX > 0 && ADX < 13;# ADX is between 0 and 13
Conditions may be nested as in this example:
Diamonds.AssignValueColor(
If BullishCondition then color.green else
If RangeCondition then color.white else
If BearishCondition then color.red else
color.black);

Note in the above, since color.green, color.white, color.red and color.black are constants and not double variables, the if-expression must be used and that requires the presence of all IF…..THEN…..ELSE parts.
Here is another example of multiple coloring in a label:
AddLabel(1, Concat("IV Percentile ", AsPercent(perct)), if perct > 0.80
then Color.Green
else if perct < 0.80 and perct > 0.50
then Color.Yellow
else color.Red);