you say they are for now, but what is the year part of the date ?
1399 ?
you are confusing me.
1399 was 621 years ago... wasnt it ? 1399 was in the 14th century. we are in the 21st century...
what am I missing ?
That makes sense, I appreciate the explanation, but now I'm unclear on your intention
Do you want to deal with these solar dates directly, and you dont want to translate to western date, but to use directly so '1399' is a number you see in the year position while you work ? or, do you want to take the custom date and manipulate it to treat as western? (so you see the 1399 as 2020 while you work ?)
what is 'the true date' ?
if you just want a list of NA's then you dont need to look at a list of input dates...
I dont understand.
I thought your original posting said one of the dates wasn't recognised as valid so turned to NA, and you wanted a better way to work with your dates, and avoid the NA.
now you want NA's ?
you can't have that date, because R's date functions (and the packages I'm aware of are for the western calendar).
thats why I provided you the integer triple representation.
Did you notice that 1399 04 31 was reproduced there, and it had no NA's ?
Timezones are about adjusting the hour based on difference from Greenwich meantime (or Coordinated Universal Time)...they are not alternate calendars as such, sorry (as far as I know)