One could probably use one of the apply family of functions (apply,
lapply, sapply), but having looked into it a bit, I think it's
simpler to use an explicit loop. I doubt you'll encounter a need for
greater efficiency, in the cpu time sense, unless your tables are
huge.
But the looping can be written more simply:
require(xtable)
df <- data.frame(nm=letters[1:4], val1=1:4, val2=round(runif(4)))
for (i in seq(nrow(df))) {
print( xtable( t(df[i,])) , type='html', include.colnames=FALSE)
cat('<br>')
}
One of the other packages for writing html from R objects might have
a function that will automatically subset a dataframe in this
particular way, but it strikes me as somewhat unlikely.
-Don
At 6:10 AM -0700 9/10/09, bbimber wrote:
hello everyone,
i'm new to R, so i hope you dont mind a fairly basic R question. we're
using R to manipulate the results of SQL queries and create an HTML output.
I'm starting with a table that looks essentially like this:
Name Field1 Field2
John value1 value2
Jane value3 value4
My table is stored as a dataframe. I'd like to efficiently produce an
output that iterates through each row, transposes it and outputs an HTML
table (one per row). like this:
Name: John
Field1: value1
Field2: value2
Name: Jane
Field1: value3
Field2: value4
I can accomplish this by looping through each row, then outputting that
row's table. This gets the job done, but it seems there must be a better
way. I'm going to need to do this sort of conversion a lot,
so the simpler the better. is there a better way to approach it than the
code below? is there a more general term for the sort of transformation i'm
trying to make that might help guide my searching?
i realize i need to look into better methods of outputting HTML tables (like
r2html).
here's the basic idea. 'labkey.data' is the data frame produced by my SQL
query:
D<-labkey.data
H<-colnames(D)
T<-t(D)
L<-length(D$id)
output <- ""
for(i in 1:L) {
R<-my.row <- D[i, ]
R<-t(R)
Len<-length(R)
output <- paste(output, "<table border=0>")
for(j in 1:Len) {
output <- paste(output,"<tr><td>", H[j],":</td><td>", R[j], "</td>")
}
output <- paste(output, "</table><p>")
}
write(output, file="${htmlout:output}")
Thanks for any help.
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--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
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