JiaxiangBU fix merge confict.
d3eff1a Feb 8, 2020
fix merge confict.
Merge branch 'master' of https://github.com/JiaxiangBU/add2ggplot

# Conflicts:
#	man/figures/README-unnamed-chunk-5-1.png
#	man/figures/README-unnamed-chunk-7-1.png
#	man/figures/README-unnamed-chunk-7-2.png
#	man/figures/README-unnamed-chunk-7-3.png
d3eff1a