I am fairly new to R and What I'd like to do is to scatter plot by category. I have a data set with 5 category (Item_nbr) and 19 variables. I want to have scatter plot for each category separately not in the same graph with different color. I mean generate 5 scatter plot. My data is :
Date Units avgdir Item_nbr tmax
1/1/2012 0 0.5 1 50
1/1/2012 2 0.2 2 40
1/1/2012 3 0.1 3 60
1/1/2012 10 0.7 4 70
1/1/2012 5 0.2 5 80
1/2/2012 6 0.8 1 90
1/2/2012 11 0.8 2 40
1/2/2012 12 0.8 3 70
1/2/2012 9 0.8 4 60
1/2/2012 8 0.8 5 70
............
Now How can I 5 scatter plot to plot units column in each of them.