On 10/13/2013 02:12 AM, anna berg wrote:
Dear R users,
I am pretty new to programming in R. So I guess there is some obvious mistake I
am making. I hope you can help me.
I have a data frame that looks like this:
AB
time x y z gene part
1 03:27:58 1 2 3 grom 1
2 03:27:58 2 3 4 grom 1
3 03:27:58 3 4 5 grom 1
4 04:44:23 12 13 14 grom 2
5 04:44:23 13 14 15 grom 2
6 04:44:23 14 15 16 grom 2
7 04:44:23 15 16 17 grom 2
8 06:23:45 101 102 103 vir 3
9 06:23:45 102 103 104 vir 3
10 06:23:45 103 104 105 vir 3
Now I want to apply a loop (here a simplified version; I know that I could do
this easily with tapply, but for the other things that I want to do with the
loop (e.g. weighted mean of time series after fast fourier transformation) I
would rather like to use a loop).
Note that "time" and "part" are actually the same, just one is a factor and the
the other is a number.
Here is the loop that works fine and returns the result as I want (the important
part here is: Intervall<- AB[AB$part==i,]):
for(i in 1:length(unique(AB$time)))
{
Intervall<- AB[AB$part==i,]
attach(Intervall)
# Standart deviation
sdx<-sd(x)
sdy<-sd(y)
sdz<-sd(z)
# Add Behavior
gene<- as.character(Intervall[1,5])
# Construct a table
tab<-c(sdx, sdy, sdz, gene)
write(tab, file=paste("VariableTable.txt", sep=""),
ncolumns=4,sep=",", append=TRUE)
detach(Intervall)
} # end of for loop
The result looks like this and is fine:
1,1,1,grom
1.3,1.3,1.3,grom
1,1,1,vir
My problem is, that I used the "part" column only to run the loop, but I
actually want to use the time column to run the loop. But when I replace
Intervall<- AB[AB$part==i,]
with
Intervall<- AB[AB$time==i,]
then the resulting table only contains NA.
I also tried to use Intervall<- AB[x==i,]
x<- as.factor(AB$part) --> which works fine as well
x<- as.factor(AB$time) --> which returns only NA
x<- unique(AB$time) ---> which returns only NA
x<- levels(unique(AB$time) --> which returns only NA
x<- seq(unique(AB$time) ---> which returns the standard deviation of the
entire column (not the single parts)
Hi Anna,
If "time" is a factor, then perhaps:
for(i in unique(AB$time)) {
...
this should also work if "time" is a character vector. I would look at:
unique(AB$time)
to see what is there.
Jim
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