CODEWITHSUNDEEP
r
emehex
emehex

Reputation: 10538

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

I have a dataframe:

zz <- "id  created  status  snap
ZX1 2012-09-07  A   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  A   2013-01-01
ZY2 2014-01-04  A   2013-01-04
ZZ3 2014-08-06  A   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 I need to pick and apply the minimum created date for each id.

Output:

id  created status  snap
ZX1 2012-09-07  A   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  A   2013-01-01
ZY2 2014-01-04  A   2013-01-04
ZZ3 2014-05-06  A   2013-01-01
ZZ3 2014-05-06  B   2013-01-03
ZZ3 2014-05-06  C   2013-01-04

Example: ZX1 "created" should be 2012-09-07 for all observations.

Upvotes: 0

Views: 28

Answers (1)

akrun
akrun

Reputation: 887158

Try

library(dplyr) 
df %>%
   group_by(id) %>%
   mutate(created=min(as.Date(created)))
#      id    created status       snap
#1 ZX1 2012-09-07      A 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      A 2013-01-01
#6 ZY2 2014-01-04      A 2013-01-04
#7 ZZ3 2014-05-06      A 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][]

Upvotes: 1

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