r - Applying the minimum date to the rest of a set of observations -

i have dataframe:

zz <- "id  created  status  snap zx1 2012-09-07    2013-01-01 zx1 2012-09-07  b   2013-01-02 zx1 2012-10-11  b   2013-01-03 zx1 2012-12-03  b   2013-01-04 zy2 2014-01-04    2013-01-01 zy2 2014-01-04    2013-01-04 zz3 2014-08-06    2013-01-01 zz3 2014-05-06  b   2013-01-03 zz3 2014-07-15  c   2013-01-04"  df <- read.table(text=zz, header=t) 

where need pick , apply minimum created date each id.

output:

id  created status  snap zx1 2012-09-07    2013-01-01 zx1 2012-09-07  b   2013-01-02 zx1 2012-09-07  b   2013-01-03 zx1 2012-09-07  b   2013-01-04 zy2 2014-01-04    2013-01-01 zy2 2014-01-04    2013-01-04 zz3 2014-05-06    2013-01-01 zz3 2014-05-06  b   2013-01-03 zz3 2014-05-06  c   2013-01-04 

example: zx1 "created" should 2012-09-07 observations.

try

library(dplyr)  df %>%    group_by(id) %>%    mutate(created=min(as.date(created))) #      id    created status       snap #1 zx1 2012-09-07      2013-01-01 #2 zx1 2012-09-07      b 2013-01-02 #3 zx1 2012-09-07      b 2013-01-03 #4 zx1 2012-09-07      b 2013-01-04 #5 zy2 2014-01-04      2013-01-01 #6 zy2 2014-01-04      2013-01-04 #7 zz3 2014-05-06      2013-01-01 #8 zz3 2014-05-06      b 2013-01-03 #9 zz3 2014-05-06      c 2013-01-04 

or using data.table

library(data.table) setdt(df)[, created1 := min(as.date(created)), by=id][]