[R] Odp: counting columns that fulfill specific criteria

[Petr PIKAL]

Hi


> Hi,
> 
> I have a matrix (pwdiff in the example below) with ~480000 rows and 780
> columns.
> For each row, I want to get the percentage of columns that have an 
absolute
> value above a certain threshold "t". I then want to allocate that 
percentage
> to matrix 'perc' in the corresponding row. Below is my attempt at doing
> this, but it does not work: I get 'replacement has length zero'. Any 
help
> would be much appreciated!!
> 
> perc<-matrix(c(1:nrow(pwdiff)))
> for (x in 1:nrow(pwdiff))
> perc[x]<-(((ncol(pwdiff[,abs(pwdiff[x,]>=t)]))/ncol(pwdiff))*100)

As 
> matrix(c(1:nrow(pwdiff)))
Error in nrow(pwdiff) : object 'pwdiff' not found
>

gives an error we cannot directly check your code.

>From what you say it seems to me that you want something like

 rowSums(pwdiff>=t, na.rm=T)/ncol(pwdiff)*100

or maybe

rowSums(abs(pwdiff)>=t, na.rm=T)/ncol(pwdiff)*100

but I can be completely wrong.

Regards
Petr

> 
> I should add that my data has NAs in some rows and not others (but I do 
not
> want to just ignore rows that have NAs)
> 
> Thanks!
> 
> Paul
> 
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> columns-that-fulfill-specific-criteria-tp3622265p3622265.html
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