I need to be able to take numbers and apply number formatting to them based on the logic of my calculation. The number formatting should be exactly the same as the "Custom" formatting that tableau does now. So, if I have a calculated parameter that should be a percentage sometimes and an integer other times, I could say
if <condition> then Format([percentage], "#.00%") else Format([integer],"#,##0.0") end
1) Allows you to format measures depending on the parameter.
Example: You want to allow the user to select whether to display a measure in thousands, millions, or units.
Case [Size Parameter] when "Thousands" then Format([number],"#,.0") when "Millions" then Format([number],"#,,.0") else format([number],"#,###.0" end
2) Gives you more granular control over how to format numbers
3) Allows logic to apply to formatting