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parsing DOB data

4 messages · Peter Nelson, Pär Leijonhufvud, Jim Lemon

Original
Peter Nelson
# 
I have a data set (.csv) with date (eg date of birth) information stored as character vectors that I?m attempting to transform to POSIXct objects using the package lubridate (1.7.4). The problem that I?m trying to address is that my two digit years are invariably (?) parsed to 20xx. For example,

x <- c("45-12-03","01-06-24","64-9-15?)
ymd(x)
[1] "2045-12-03" "2001-06-24" "2064-09-15?

These should be parsed as ?1945-12-03? ?2001-06-24? ?1964-09-15?. 

I've tried to use parse_date_time()?based on the documentation it looks to me as though the argument cutoff_2000 should allow me to address this, but it?s unclear to me how to implement this. As an example, I?ve tried

parse_date_time(x, cutoff_2000 = 01)

but get the following error message (and similar for other similar attempts, including cutoff_2000 = 01L)

Error in parse_date_time(x, cutoff_2000 = 1) : 
  unused argument (cutoff_2000 = 1)

Thanks for your help!

Peter Nelson, PhD
Institute of Marine Sciences
University of California, Santa Cruz
Center for Ocean Health, Long Marine Lab
115 McAllistair Way
Santa Cruz, CA, 95076, USA
707-267-5896
Pär Leijonhufvud
# 
Hi!

For more solutions look at https://stackoverflow.com/questions/33221603/r-lubridate-returns-unwanted-century-when-given-two-digit-year

The  proposed solution:
   some_dates <- c("3/18/75", "March 10, 1994", "10/1/80", "June 15, 1979")
   dates <- mdy(some_dates)
   future_dates <- year(dates) > year(Sys.Date())
   year(dates[future_dates]) <- year(dates[future_dates]) - 100

Should work for your case with one adaption (change mdy to ymd). At least it worked on your example.

Yours,

/P?r

--
P?r Leijonhufvud               .                                    par.leijonhufvud at regionjh.se
Sjukhuskemist                                                        +46(0)63-153 376, +46-(0)70-242 7006
Laboratoriemedicin
?stersunds sjukhus

-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of Peter Nelson via R-help
Sent: den 15 april 2020 20:31
To: r-help at r-project.org
Subject: [R] parsing DOB data

I have a data set (.csv) with date (eg date of birth) information stored as character vectors that I?m attempting to transform to POSIXct objects using the package lubridate (1.7.4). The problem that I?m trying to address is that my two digit years are invariably (?) parsed to 20xx. For example,

x <- c("45-12-03","01-06-24","64-9-15?)
ymd(x)
[1] "2045-12-03" "2001-06-24" "2064-09-15?

These should be parsed as ?1945-12-03? ?2001-06-24? ?1964-09-15?.

I've tried to use parse_date_time()?based on the documentation it looks to me as though the argument cutoff_2000 should allow me to address this, but it?s unclear to me how to implement this. As an example, I?ve tried

parse_date_time(x, cutoff_2000 = 01)

but get the following error message (and similar for other similar attempts, including cutoff_2000 = 01L)

Error in parse_date_time(x, cutoff_2000 = 1) :
  unused argument (cutoff_2000 = 1)

Thanks for your help!

Peter Nelson, PhD
Institute of Marine Sciences
University of California, Santa Cruz
Center for Ocean Health, Long Marine Lab
115 McAllistair Way
Santa Cruz, CA, 95076, USA
707-267-5896







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Jim Lemon
# 
Hi Peter,
One way is to process the strings before converting them to dates:

x2<-c("45-12-03","01-06-24","04-9-15","1901-03-04")
add_century<-function(x,changeover=68,previous=19,current=20) {
 centuries<-sapply(sapply(x,strsplit,"-"),"[",1)
 shortyears<-which(!(nchar(centuries)>2))
 century<-rep("",length(x))
 century[shortyears]<-ifelse(centuries[shortyears]>changeover,previous,current)
 newx<-paste0(century,x)
 return(newx)
}
add_century(x2,1)

Jim

On Fri, Apr 17, 2020 at 12:34 AM Peter Nelson via R-help
<r-help at r-project.org> wrote:
Jim Lemon
# 
Hi Peter,
I worked out a neat function to add the century to short dates. It
works fine on its own, but sadly it bombs when used with sapply. Maybe
someone else can point out my mistake:

add_century<-function(x,changeover=68,previous=19,current=20,pos=1,sep="-") {
 xsplit<-unlist(strsplit(x,sep))
 # only add century to short dates
 if(nchar(xsplit[pos]) < 3) {
  century<-ifelse(as.numeric(xsplit[pos]) <= changeover,current,previous)
  xsplit[pos]<-paste0(century,xsplit[[pos]])
 }
 return(paste(xsplit,collapse=sep))
}
# these work
add_century(x3[1],changeover=1,pos=3,sep="/")
add_century(x3[2],changeover=1,pos=3,sep="/")
add_century(x3[3],changeover=1,pos=3,sep="/")
# this doesn't
sapply(x3,add_century,list(changeover=1,pos=3,sep="/"))

Jim
On Fri, Apr 17, 2020 at 11:30 AM Jim Lemon <drjimlemon at gmail.com> wrote: