coldata
date value
1 2006-09-30 0.690
2 2007-09-30 1.837
3 2008-09-30 2.400
4 2009-09-30 2.401
5 2010-09-30 3.255
6 2011-09-30 3.910
7 2012-09-30 3.070
8 2013-09-30 4.000
str(coldata)
'data.frame': 8 obs. of 2 variables:
$ date : Factor w/ 8 levels "2006-09-30","2007-09-30",..: 1 2 3 4 5 6 7 8
$ value: num 0.69 1.84 2.4 2.4 3.25 ...
t<-ggplot(data=coldata,mapping=aes(date,value))
t+geom_point()#正常显示，
t+geom_line()#不正常显示
