Gridlines are the horizontal and vertical dotted lines, and they help to organize the chart so that the values on the labels becomes better readable to viewers. This is helpful specially in situations where we plot a large number of data points. A graph drawn by plot function can have gridlines by defining the vertical and horizontal lines using abline.
Consider the below data and scatterplot −
> x<-rnorm(10) > y<-rnorm(10,1.5) > plot(x,y)
Adding gridlines using abline function −
> abline(h=seq(0,5,0.5),lty=5) > abline(v=seq(-2,2,0.5),lty=5)