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

[tsunhin wong]

Thanks Jim and All!

It works:
tmptrial <- trialcompute(trialextract(
get(paste("t",tmptrialinfo[1,2],tmptrialinfo[1,16],".gz",sep="")) ,
tmptrialinfo[1,32],secs,sdm),secs,binsize)

Can I use "assign" instead? How should it be coded then?

Thanks!

- John

On Mon, Dec 8, 2008 at 10:40 AM, Jim Holtman <jholtman at gmail.com> wrote:
> ?get
>
>
> Sent from my iPhone
>
> On Dec 8, 2008, at 7:11, "tsunhin wong" <thjwong at gmail.com> wrote:
>
>> 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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>