Re: [R] Conditionally constructing columns in a data frame

From: David Winsemius <dwinsemius_at_comcast.net>
Date: Tue, 29 Jun 2010 15:36:00 -0400

On Jun 29, 2010, at 2:54 PM, Stuart Luppescu wrote:

> Hello, I have to construct 5 new columns in a data frame depending on
> the value of another of the columns in the data frame. The only way I
> could figure out to do this was to subset the data frame five times,
> do
> the variable construction, and then rbind the subsets back together.
> Here's part of the code I used:
>
> read001 <- read[read$=="001",]
>
> read001$era1end <- NA
> read001$era2base <- NA
> read001$era2end <- NA
> read001$era3base <- read001$era1base
> read001$era3end <- read001$era3base + (6 * read001$era3tr)
>
> read011 <- read[read$existstr=="011",]
>
> read011$era1end <- NA
> read011$era2base <- read011$era1base
> read011$era2end <- read011$era2base + (4 * read011$era2tr)
> read011$era3base <- read011$era2end
> read011$era3end <- read011$era2end + (6 * read011$era3tr)
>
> ...

?split

processed_list <- split(read, read$existstr) # then you have the dataframe in sections determined by existstr's value # process within groups (but your example does not generalize in an obvious manner.)
# then:
final <- do.call(rbind , processed_list)

-- 
David.

>
> read2 <- rbind(read001, read011, read100, read110, read111)
>
>
> Isn't there an easier way to do this?
>
> Thanks.
>
> --
> Stuart Luppescu <slu_at_ccsr.uchicago.edu>
> University of Chicago
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD West Hartford, CT ______________________________________________ R-help_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Received on Tue 29 Jun 2010 - 19:39:56 GMT

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