How to print a date when the input is number of days since 01-01-60? - r

Question

I received a set of dates, but it turns out that time is reported in days since 01-01-1960 in this specific data set.
D_INDDTO
1 20758
2 20856
3 21062
4 19740
5 21222
6 21203
The specific date of interest for Patient 1 is 20758 days since 01-01-60
I want to create a new covariate u$date containing the specific date of interest i d%m%y%. I tried
library(tidyverse)
u %>% mutate(date=as.date(D_INDDTO,origin="1960-01-01")
But that did not solve it.
u <- structure(list(D_INDDTO = c(20758, 20856, 21062, 19740, 21222,
21203, 20976, 20895, 18656, 18746)), row.names = c(NA, 10L), class = "data.frame")

Answer 1

Try this:
#Code 1
u %>% mutate(date=as.Date("1960-01-01")+D_INDDTO)
Output:
D_INDDTO date
1 20758 2016-10-31
2 20856 2017-02-06
3 21062 2017-08-31
4 19740 2014-01-17
5 21222 2018-02-07
6 21203 2018-01-19
7 20976 2017-06-06
8 20895 2017-03-17
9 18656 2011-01-29
10 18746 2011-04-29
Or this:
#Code 2
u %>% mutate(date=as.Date(D_INDDTO,origin="1960-01-01"))
Output:
D_INDDTO date
1 20758 2016-10-31
2 20856 2017-02-06
3 21062 2017-08-31
4 19740 2014-01-17
5 21222 2018-02-07
6 21203 2018-01-19
7 20976 2017-06-06
8 20895 2017-03-17
9 18656 2011-01-29
10 18746 2011-04-29
Or this:
#Code 3
u %>% mutate(date=format(as.Date(D_INDDTO,origin="1960-01-01"),'%d%m%y'))
Output:
D_INDDTO date
1 20758 311016
2 20856 060217
3 21062 310817
4 19740 170114
5 21222 070218
6 21203 190118
7 20976 060617
8 20895 170317
9 18656 290111
10 18746 290411
If more customization is required:
#Code 4
u %>% mutate(date=format(as.Date(D_INDDTO,origin="1960-01-01"),'%d-%m-%Y'))
Output:
D_INDDTO date
1 20758 31-10-2016
2 20856 06-02-2017
3 21062 31-08-2017
4 19740 17-01-2014
5 21222 07-02-2018
6 21203 19-01-2018
7 20976 06-06-2017
8 20895 17-03-2017
9 18656 29-01-2011
10 18746 29-04-2011