I am currently doing my school activities with regards on creating a line graph by quarter and this is my error that is keep on prompting even I debug it many times

for(i in 1:4){current_quarter <- subset (shipment.ts,cycle (shipment.ts)==i)lines(current_quarter,type="b", lwd=1.5, lty=linetype[i], col=color[i], pch=plotchar[i])}

Hi!

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