Difference between ggplot and scatter plot
I have two doubts..Would be grateful if you could clear that..
1) what is the difference between ggplot and a simple scatter plot which we plot through plot command ? Whats the additional advantage we have over using ggplot instead of a scatter plot ?
2) When we want to plot two graphs together..it has to be one plotted through plot and other through line ?
R Introduction-to-ggplot2 10-11 min 10-20 sec
For your first query, i.e when and why to use ggplot, you should read the explanation given here: http://varianceexplained.org/r/why-I-use-ggplot2/
There are a couple of ways to draw two plots together, as given here: https://stackoverflow.com/questions/2564258/plot-two-graphs-in-same-plot-in-r