[R] replace numbers in a column conditional on their value

[Erik Iverson]

Try something like,

##Untested
zz$FC <- ifelse(zz$FC > 2, zz$FC^2, zz$FC)

and see
?ifelse

-Erik Iverson

Jabez Wilson wrote:
> Dear R help,
>    
>   I have a data frame column in which I would like to replace some of the numbers dependent on their value.
>    
>   data frame = zz
>    
>   AveExpr         t      P.Value       FC
> 7.481964  7.323950 1.778503e-04 2.218760
> 7.585783 12.233056 6.679776e-06 2.155867
> 6.953215  6.996525 2.353705e-04 1.685733
> 7.647513  8.099859 9.512639e-05 1.674742
> 7.285446  7.558675 1.463732e-04 1.584071
> 6.405605  3.344031 1.276812e-02 1.541569
> 
>   I would like to replace the values in column 'FC' which are >2 with their squared value.
>   If I do this, however, I get a warning but it does the sum correctly.
>   Warning message:
> number of items to replace is not a multiple of replacement length in: zz[, 4][zz[, 4] > 2] <- zz[, 4]^2 
>    
>   Is there a way to do this without the warning?
>    
> 
>        
> ---------------------------------
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.