<br />
library(dplyr)<br />
data.frame(a=c('20140101','20140102','20140103'),b=1:3) %>%mutate(a2=strptime(a, '%Y%m%d'))<br />
Error: wrong result size (11), expected 3 or 1<br />
为啥我用strptime将文本日期转为POSIXct日期, dplyr会认为a2的长度是11而不是3?
<br />
> strptime(c('20140101','20140102','20140103'), '%Y%m%d')<br />
[1] "2014-01-01 CST" "2014-01-02 CST" "2014-01-03 CST"<br />
结果应该是一个长度为3的向量啊.
</p>