perlatex
`mm <- read.table("data.txt", header = TRUE, sep = "", encoding='UTF-8')
library("ggplot2")
theme_set(theme_bw())
library("viridis")
ggplot(mm)+
geom_point(aes(x=univ,y=dis,colour=year, size=paper))+
scale_color_viridis()+
scale_size(range=c(2,18))
===============data.txt===================
num univ dis paper cited year
1 Beijing Physics 193 4555 2005
2 Beijing Physics 197 2799 2006
3 Beijing Physics 240 2664 2007
4 Beijing Physics 200 3191 2008
5 Beijing Physics 268 2668 2009
6 Beijing Physics 249 2300 2010
7 Beijing Physics 262 2080 2011
8 Beijing Physics 230 2371 2012
9 Beijing Physics 309 1367 2013
10 Beijing Physics 284 615 2014
11 Beijing Chemistry 143 1650 2005
12 Beijing Chemistry 149 2379 2006
13 Beijing Chemistry 190 2566 2007
14 Beijing Chemistry 147 1888 2008
15 Beijing Chemistry 184 2146 2009
16 Beijing Chemistry 214 2568 2010
---
=====================================
问题：时间标签变成了 2005.0 2007.5 2010.0 2012.5
而不是我想要的 2005 2007 2010 2012
求大神帮忙
