How to convert a data frame column to date that contains integer values in R?

If we have an integer column that actually contains date values, for example having 29th September 2020 as 20200929 then we can convert it to date by using transform function by reading the dates with as.Date function but as.character will also be needed so that as.Date function can read the date values.

Example1

S.NO<−1:20
Date<−c(19980313, 19980604, 19980409, 19980104, 19980501, 19980101, 19980521, 19980412, 19980601, 19980711, 19980615, 19980810, 19980509, 19980221, 19981101, 19981121, 19981009, 19980915, 19980929, 19980813)
df2<−data.frame(S.NO,Date)
df2

Output

   S.NO    Date
1 1 19980313
2 2 19980604
3 3 19980409
4 4 19980104
5 5 19980501
6 6 19980101
7 7 19980521
8 8 19980412
9 9 19980601
10 10 19980711
11 11 19980615
12 12 19980810
13 13 19980509
14 14 19980221
15 15 19981101
16 16 19981121
17 17 19981009
18 18 19980915
19 19 19980929
20 20 19980813

Converting Date to appropriate date format −

df2<−transform(df2,Date=as.Date(as.character(Date),"%Y%m%d"))
df2

Output

   S.NO    Date
1 1 1998−03−13
2 2 1998−06−04
3 3 1998−04−09
4 4 1998−01−04
5 5 1998−05−01
6 6 1998−01−01
7 7 1998−05−21
8 8 1998−04−12
9 9 1998−06−01
10 10 1998−07−11
11 11 1998−06−15
12 12 1998−08−10
13 13 1998−05−09
14 14 1998−02−21
15 15 1998−11−01
16 16 1998−11−21
17 17 1998−10−09
18 18 1998−09−15
19 19 1998−09−29
20 20 1998−08−13