[R] Date

[Val]

IHi All, l,

I am  reading a csv file  and one of the columns is named as  "mydate"
 with this form, 2019-09-16.

I am reading this file as

dat=read.csv("myfile.csv")
     the structure of the data looks like as follow

str(dat)
mydate : chr  "09/16/2019" "02/21/2021" "02/22/2021" "10/11/2017" ...

Please note the format  has  changed from YYYY-mm-dd  to mm/dd/YYYY
When I tried to change this   as a Date using

as.Date(as.Date(mydate,     format="%m/%d/%Y" )
I am getting this error message
    Error in charToDate(x) :
      characte string is not in a standard unambiguous format

My question is,
1. how can I read the file as it is (i.e., without changing the date format) ?
2. why does R change the date format?

Thank you,