求助，在R中运行到最下面出现error mapping` must be created by `aes()，这是哪里出了问题，明明以前也是这样写ggplot 里的
画图，怎么这次就出错了？完全无头绪！！
～～～～～～～～～
a=c(1,2,3,1,2,3)
b=c(1,1,1,2,2,2)
y=c(27,21,33,15,6,11)
k=c(295,416,308,474,540,498)
aa=as.factor(a)
bb=as.factor(b)
options(contrasts=c("contr.sum","contr.sum"))
collator.out=glm(y~aa+bb,family = poisson,offset = log(k))
summary(collator.out)
collator.fit=predict.glm(collator.out,type = 'response',se.fit=TRUE)
y.fit=collator.fit$fit
y.sef=collator.fit$se.fit
yfL=y.fit-2*y.sef
yfH=y.fit+2*y.sef
data.jam=data.frame(a,aa,b,bb,y,y.fit,y.sef,yfL,yfH)
library(ggplot2)
w=ggplot(data.jam,mapping = aes_(a,y))
w + geom_point(data.jam, aes_(a,y,color=b))