[R] Getting a column of values from a list - think I'm doing it the hard way

Ronggui Huang ronggui.huang at gmail.com
Thu Jun 4 04:57:28 CEST 2009


2009/6/4 Jason Rupert <jasonkrupert at yahoo.com>:
>
> Example code it shown below.
>
> I think I am doing this the hard way.  I'm just trying to get the full year value from an array of dates.  An example array is shown below.  Right now, I'm using a "for" loop to pull the year out of a list where the dates were split up into their individual components.
>
> This seems to work, but just wondering if there is an easier way.
>
> Thanks for any insights.
>
> #*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~
> HouseDates <- c("02/27/90", "02/27/91", "01/14/92", "02/28/93", "02/01/94", "02/01/95", "02/01/96")
>
> # ?as.Date
> HouseDatesFormatted<-as.Date(HouseDates, "%m/%d/%y")
>
> HouseDatesFormatted
>
> HouseDatesList<-strsplit(as.character(HouseDatesFormatted), "-", fixed=TRUE)

> sapply(HouseDatesList,function(x) x[[1]])
[1] "1990" "1991" "1992" "1993" "1994" "1995" "1996"


> HouseYear_array<-NULL
> length_array<-length(HouseDatesList)
> for(ii in 1:length_array)
> {
>        HouseYear<-HouseDatesList[[ii]][1]
>
>        HouseYear_array<-c(HouseYear_array, HouseYear)
> }
>
> as.character(HouseYear_array)
>
> # Desired:
> # [1] "1990" "1991" "1992" "1993" "1994" "1995" "1996"
>
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>



-- 
HUANG Ronggui, Wincent
PhD Candidate
Dept of Public and Social Administration
City University of Hong Kong
Home page: http://asrr.r-forge.r-project.org/rghuang.html




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