[R] R-code help for filtering with for loop

[David Winsemius]

The apply function which can work on either a row-wise of column-wise  
basis can be used with max  and ">" can return a logical vector that  
will let you separate the rows into those with and without a maximum  
greater than 60.

 > datax <- matrix(rnorm(300)*30,nrow=50)
 > datax <- as.data.frame(datax)

datax[ apply(datax, 1 ,max) >= 64, ]  # the rows from datax with any  
value greater than 64
datax[ apply(datax, 1 ,max) < 64, ]   # the other rows

I am not sure what you mean by a table, since in R "table" generally  
means a contingency table. If you wanted a vector of row numbers, this  
might help:

  which(apply(datax,1,max) > 60)  # [1]  7 17 22 25 29 46 49

-- 
David Winsemius


On Mar 2, 2009, at 5:30 AM, John Antonydas Gaspar wrote:

> Dear Sir / Madam,
>
> I am new for R coding. Kindly help me out in sorting out the  
> following problem.
>
> There are 50 rows with six coloumns(you could see in the  
> attached .txt file). I
> wish to go for filtering this 50 rows for any one of the six coloumns
> satisfying the value >= 64.
>
> I need to have a final table with rows having >= 64 value in any one  
> of the six
> coloumns and the rest could be <=64. For this purpose I use the  
> following R
> code;
> ---------------
> datax<- 
> read.table("filter_test.txt",row.names=1,sep="\t",header=TRUE,dec =
> ".",as.is =TRUE,na.strings = "NA", colClasses = NA,check.names =
> FALSE,strip.white = FALSE, blank.lines.skip = TRUE,
> allowEscapes = FALSE, flush = FALSE,encoding = "unknown")
>
>
> filter<-datax[,1:6]
>
> filtered<-vector()
>
> for(i in 1:(dim(filter)[1]))
> {
> for(j in 1:(dim(filter)[2]))
> {
> x=(filter[i,j])>=64
> filtered[i]<-x
> }
> }
>
> # summing the result of the above
> sum(filtered)
>
>
> which(filtered)
> z<-which(filtered)
> filereddata<-filter[z,]
>
>
> write.table(filtereddata,file ="filterdgenes.txt",quote = TRUE, sep  
> = "\t ",
>            dec = ".",row.names=T,col.names = NA, qmethod = c (escape",
> "double"))
>
> ---------------------------
>
>
> There is something is missing in my coding therefore the filteration  
> is done
> according to the value of the last column that is the sixth coloumn  
> value not
> takiing into consideration the rest of the coloumns.
>
> For example with the table in .txt file I have attached, the first  
> coloumn has
> 29 rows having values >= 64 but the last coloumn has only 25 rows.
>
> The filtered list should have around 29 rows but only 25 since the  
> coding has
> considered only the last coloumn.  How to sort out this problem.  
> Kindly help me
> out.
>
> Thanking in advance,
> With Regards,
>
> antony
>
>
> -- 
> Thony
> University of Cologne
> 50931 Cologne/Germany
>
> Tel:  004922125918042
> Handy:   004917683142627
>
>
>
>
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