[R] replacing rows data.frame

[Rui Barradas]

Hello,

Your problem comes from the fact that as new values are inserted in 
'alloc' the column alloc$agi keeps changing (obvious!) therefore R can't 
know all the factor levels beforehand. Therefore the values inserted are 
the numeric codes of the original factor. Since your example doesn't 
run, I've made up a dataset. Try to see what happens.


x <- data.frame(A = letters[1:10], B = 1:10)
str(x)

y <- data.frame(matrix(nrow=5, ncol=2))
colnames(y) <- colnames(x)

for(i in 1:10){
     if(i %% 2 == 0){  # example condition
         y[i/2, 1] <- as.character(x[i, 1])  # the factor column
         y[i/2, -1] <- x[i, -1]  # all but 1st column
     }
}
y$A <- factor(y$A)  # in the end we know the levels.
str(y)


Likewise, you must first fill in the column with character values then, 
in the end, coerce to factor.

Hope this helps,

Rui Barradas
Em 19-10-2012 12:06, evelyne escreveu:
> I create a data.frame using :
> alloc <- data.frame(matrix(nrow=length(unique(mid2agi$gene)), ncol=8))
> colnames(alloc) <- c('agi', 'hit_len', 'q_len', 'identity', 'ratio', 'e',
> 'ok' ,'gene')
> alloc$gene <- unique(mid2agi$gene)
>
> this results in:
>> head(alloc)
>   agi hit_len q_len identity   ratio          e    ok           gene
> NA NA NA NA NA NA NA BrChr1g00001V4
> NA NA NA NA NA NA NA BrChr1g00002V4
>
> and I already have a dataframe (mid2agi) containing both integers and
> factors.
> In my empty dataframe I want to replace rows using:
>
> for (i in (1:nrow(alloc)) ) {
>      find <- alloc[i,]$gene
>      submid2agi <- subset(mid2agi, gene %in% find)
>      max <- which.max(submid2agi$identity * submid2agi$ratio)
>      if (length(max) > 0){
>         *alloc[i,] <- submid2agi[max,]*
>     }
> }
>
> But my problem is that all values are now interpreted as integers, so my
> text in my factors are converted to numbers.
> Can anyone provide me with tips on how to solve this?
>
> ouoput:
> agi hit_len q_len identity   ratio          e ok           gene
> *18296*     344   551   86.919 0.62432 2.1142e-89  *2* BrChr1g00001V4
>
> SHOULD be:
>   agi hit_len q_len identity   ratio          e    ok           gene
> AT4G38360.2     344   551   86.919 0.62432 2.1142e-89  True BrChr1g00001V4
>
> Thanks you..
> Evelyne
>
>
>    
>
>
>
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