[R] conditional data replace (recode, change or whatsoever)

[R. Michael Weylandt <michael.weylandt@gmail.com>]

As others have noted, this is discussed in many free R tutorials, but if you want to do it in one line I think this should do it:

X[is.NA(X[,"b"])&(X[,"c"]==0),"b"]<-"2011-07-28" #where X is the name of the data frame. 

It's a somewhat convoluted line of code but if you read it inside out the logic is clear:

Find those rows where column b is NA and c is 1 by searching all rows of the relevant column (the X[,something] syntax): select those rows and the b column. Put the desired date in those slots. let me know of I can further clarify this. I changed the date assuming a typo on your end. 

Welcome and good luck getting started with R,

Michael Weylandt


On Aug 3, 2011, at 4:05 AM, zcatav <zcatav at gmail.com> wrote:

> Hello,
> I have a big data.frame, a piece of it as follows.
> 
>   a            b                c        d
> 1    58009    2010-11-02    0        NA
> 2    114761    NA                1        2008-11-05
> 3    184440    NA                1        2009-12-08
> 4    189372    NA                0        NA
> 5    105286    NA                0        NA
> 6    186717    NA                0        NA
> 7    189106    NA                0        NA
> 8    127306    NA                0        NA
> 9    157342    2011-04-25    0        NA
> 
> I want to replace b[NA] values with "20011-07-28" where c==0. I use rstudio
> and i'm a novice.
> 
> 
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