user  distance time
1    1  8.559737    4
2    1  5.013872    5
3    1 11.168995    9
4    1  4.059428    4
5    1  3.928071    4
6    1 12.403195    7

plot <- ggplot(scatter, aes(x=scatter[['distance']], y=scatter[['time']])) +
          geom_point(shape=16, size=5, colour=scatter[['user']]) +
          scale_x_continuous("Distance", limits=c(0,100), breaks=seq(0, 100, 10)) +
          scale_y_continuous("Time", limits=c(0,20), breaks=seq(0, 20, 2))

png(filename="scatters/0_2_scatter.png", width=800, height=800)
plot(plot)
dev.off()