Libraries

library(lubridate) #dates conversion package
library(DT) #table package
library(rio)
install_formats()
## [1] TRUE

Import Data

data<-import("E:\\New folder\\data.xlsx")

#subset the data
date_unconverted<-data[1:3]

Structure of the Data

str(date_unconverted)
## 'data.frame':    309 obs. of  3 variables:
##  $ SubmissionDate: chr  "2019-08-14T13:54:13.784Z" "2019-08-14T13:51:03.457Z" "2019-08-14T13:54:04.777Z" "2019-08-14T13:50:18.188Z" ...
##  $ starttime     : chr  "2019-08-14T10:40:57.028+03" "2019-08-14T15:07:32.591+03" "2019-08-14T09:46:59.358+03" "2019-08-14T11:42:42.228+03" ...
##  $ endtime       : chr  "2019-08-14T16:44:14.403+03" "2019-08-14T15:28:13.059+03" "2019-08-14T16:49:21.161+03" "2019-08-14T15:06:17.162+03" ...
DT::datatable(date_unconverted,class = 'cell-border stripe',rownames = F,caption = "Table 1: Un-converted Dates",options = list(columnDefs = list(list(className = 'dt-center', targets = 0:2))))

Convert the Dates

dates<-data[1:3]

dates$SubmissionDate<-date(dates$SubmissionDate)
dates$starttime<-date(dates$starttime)
dates$endtime<-date(dates$endtime)

Converted Dates Output

datatable(dates,class = 'cell-border stripe',rownames = F,caption = "Table 2: Converted Dates",options = list(columnDefs = list(list(className = 'dt-center', targets = 0:2))))