How to change mulitiple characters in a column to a date

Question

There are so many columns that I want to change from multiple characters to Date. I have tried Mutate function

Here is the Sample data:

d1 = c("2018-02-07 23:00:00", "2018-06-03 00:00:01", "2018-05-09
00:00:01")
d2 = c("2018-01-11 08:41:49", "2016-09-10 08:39:48", "2016-02-17
         08:41:51")
dataf<-as.data.frame(cbind(col1,col2))

Got an error by using mutate:

dataf<- dataf %>% mutate (dataf, funs(ymd))

Answer 1

Firstly we have to set dataf variable to Data Frame

dataf<-as.data.frame(cbind(d1,d2))

dataf$d1<-as.Date(dataf$d1)
dataf$d2<-as.Date(dataf$d2)

Now our Mulitiple characters have been change to Date Format 

 d1         d2
1 2018-02-07 2018-01-11
2 2018-06-03 2016-09-10
3 2018-05-09 2016-02-17

By str (Structure) commad we can verify

'data.frame':	3 obs. of  2 variables:
 $ d1: Date, format: "2018-02-07" "2018-06-03" ...
 $ d2: Date, format: "2018-01-11" "2016-09-10" ...