You can also plot to a png file using gnuplot (which is free):
terminal commands
gnuplot> set title '<title>'
gnuplot> set ylabel '<yLabel>'
gnuplot> set xlabel '<xLabel>'
gnuplot> set grid
gnuplot> set term png
gnuplot> set output '<Output file name>.png'
gnuplot> plot '<fromfile.csv>'
note: you always need to give the right extension (.png here) at set output
Then it is also possible that the ouput is not lines, because your data is not continues. To fix this simply change the 'plot' line to:
plot '<Fromfile.csv>' with line lt -1 lw 2
More line editing options (dashes and line color ect.) at: http://gnuplot.sourceforge.net/demo_canvas/dashcolor.html
apt-get install gnuplot)brew install gnuplot)