如下，我已经保留了两位有效数字，但最终输出为csv格式时还是以前的数字，为什么呢
> options(digits=2)
> h
  [,1]        [,2] [,3] [,4] [,5]  [,6]
u "changchun" 7.2  7.2  7.2  0.038 40  
u "nanchang"  7.2  7.2  7.2  0.04  33  

输出为
> write.csv(h,file="h")
changchun,7.19205910619894,7.19830610283518,7.21589380105718,0.0376667538582265,40.3086627082595
nanchang,7.15939748953975,7.15931380753138,7.1597489539749,0.0398848684210526,32.8698630136986

完全没变，怎么办呢？我试了用round(h,2)报错了，因为其中含有list