[R] Date

[PIKAL Petr]

Hi

Not sure why the date format was changed but if I am correct R do not read dates as dates but as character vector. You need to transfer such columns to dates by asDate. The error is probably from your use two asDate commands.

Cheers
Petr
-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Val
Sent: Thursday, November 4, 2021 10:43 PM
To: r-help using R-project.org (r-help using r-project.org) <r-help using r-project.org>
Subject: [R] Date

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,

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