[R] Cleaning date columns

[Bill.Venables at csiro.au]

Here is one possible way (I think - untested code)


cData <- do.call(rbind, lapply(split(data, data$prochi), 
	function(dat) {
		dat <- dat[order(dat$date), ]
		while(any(d <- (diff(dat$date) <= 3))) 
			dat <- dat[-(min(which(d))+1), ]
		dat
	}))

(It would be courteous of you to give us your real name, by the way) 

Bill Venables.

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Newbie19_02
Sent: Wednesday, 9 March 2011 9:20 PM
To: r-help at r-project.org
Subject: [R] Cleaning date columns

Hi Everyone,

I have the following problem:

data <- structure(list(prochi = c("IND1", "IND1", "IND1", 
"IND2", "IND2", "IND2", "IND2", "IND3", 
"IND4", "IND5"), date_admission = structure(c(6468, 
6470, 7063, 9981, 9983, 14186, 14372, 5129, 9767, 11168), class = "Date")),
.Names = c("prochi", 
"date_admission"), row.names = c("27", "28", "21", "86", "77", 
"80", "1", "114", "192", "322"), class = "data.frame")


I have records for individuals that were taken on specific dates.  Some of
the dates are within 3 days of each other.  I want to be able to clean my
date column and select the earliest of the dates that occur within 3 days of
each other per individual as a single observation that represents the N
observations.  So for example:

input:
IND1    1987-09-17
IND1     1987-09-19
IND1     1989-05-04

output:
IND1    1987-09-17
IND1     1989-05-04

I'm  not sure where to start with this?

Thanks,
Nat
 

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