[R] Transforming a string to a variable's name? help me newbie...

tsunhin wong thjwong at gmail.com
Mon Dec 8 16:11:35 CET 2008


Dear all,

I'm a newbie in R.
I have a 45x2x2x8 design.
A dataframe stores the metadata of trials. And each trial has its own
data file: I used "read.table" to import every trial into R as a
dataframe (variable).

Now I dynamically ask R to retrieve trials that fit certain selection
criteria, so I use "subset", e.g.
tmptrialinfo <- subset(trialinfo, (Subject==24 & Filename=="v2msa8"))

The name of the dataframe / variable of an individual trial can be
obtained using:
paste("t",tmptrialinfo[1,2],tmptrialinfo[1,16],".gz",sep="")
Then I get a string:
"t24v2msa8.gz"
which is of the exact same name of the dataframe / variable of that
trial, which is:
t24v2msa8.gz

Can somebody tell me how can I change that string (obtained from
"paste()" above) to be a usable / manipulable variable name, so that I
can do something, such as:
(1)
tmptrial <- trialcompute(trialextract(
paste("t",tmptrialinfo[1,2],tmptrialinfo[1,16],".gz",sep="")
,tmptrialinfo[1,32],secs,sdm),secs,binsize)
instead of hardcoding:
(2)
tmptrial <- trialcompute(trialextract(t24v2msa8.gz,tmptrialinfo[1,32],secs,sdm),secs,binsize)

Currently, 1) doesn't work...

Thanks in advance for your help!

Regards,

      John



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