I have data formatted like this in a csv file: a, 1, 4, 6.0 a, 2, 42, 16.0 a, 5, 14, 69.3 a, 11, 4, 7.0 b, 1, 45, 6.0 b, 2, 45, 1.9 b, 9, 2, 4.4 b, 11, 4, 7.9 lines with first parameter a is one set of data, and first parameter b represents another set. My aim is to plot two lines on the same graph, one with points (1, 4, 6.0), (2, 42, 16.0), (5, 14, 69.3), (11, 4, 7.0) and the other with points (1, 45, 6.0), (2, 45, 1.9), (9, 2, 4.4), (11, 4, 7.9) I am able to import the data directly in MS Excel, but am not sure how to plot them. How can I plot this data?