Plotting within a Loop, Cannot use 'plot' in local scope. (TradingView Pine Script)

Question

I am having trouble figuring out the proper implementation while trying to clean up my code and I found a section that seemed ripe for a For-loop, however, I receive the following error:

Cannot use 'plot' in local scope. 

When trying to do the following example:

a = 10
b = 5
for i = 1 to b
    j = a * i
    plot(highest(j), title="Resistance", color=b, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)

My original code is as follows:

a=10
plot(highest(a*1), title="Resistance", color=color.green, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)
plot(highest(a*2), title="Resistance", color=color.green, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)
plot(highest(a*3), title="Resistance", color=color.green, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)
plot(highest(a*4), title="Resistance", color=color.green, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)
plot(highest(a*5), title="Resistance", color=color.green, linewidth=2, style=plot.style_line, transp=d, offset=-9999, trackprice=true)

I ultimately would like to have the number of plots(the b variable) adjustable from say 0 to 20 and thus just writting out all the plot lines doesn't really work.

What is the proper way to implement this in Pine?

Thank you!

Answer 1

Your script draw horizontal lines.
With version 5, you can use line in local scope :

a = 10
b = 5
for i = 1 to b
    j = a * i
    line.new(bar_index-1, ta.highest(j), bar_index, ta.highest(j), extend=extend.both)

and get a result like that :