string - 如何从日期字符变量中删除时间字段字符串？

Question

假设我有一个这样的变量

c<-c("9/21/2011 0:00:00",  "9/25/2011 0:00:00",  "10/2/2011 0:00:00",  
"9/28/2011 0:00:00",  "9/27/2011 0:00:00")

有什么快速方法可以删除所有 0:00:00 以便

c
[1] "9/21/2011" "9/25/2011" "10/2/2011" "9/28/2011" "9/27/2011"

Answer 1

您可以将它们转换为日期，然后根据需要设置格式，例如:

v <- c("9/21/2011 0:00:00",  "9/25/2011 0:00:00",  "10/2/2011 0:00:00",  
     "9/28/2011 0:00:00",  "9/27/2011 0:00:00")
v <- format(as.POSIXct(v,format='%m/%d/%Y %H:%M:%S'),format='%m/%d/%Y')
> v
[1] "09/21/2011" "09/25/2011" "10/02/2011" "09/28/2011" "09/27/2011"

或者，您可以简单地使用 gsub 删除"0:00:00" 子字符串:

v <- gsub(x=v,pattern=" 0:00:00",replacement="",fixed=T)
> v
[1] "9/21/2011" "9/25/2011" "10/2/2011" "9/28/2011" "9/27/2011"