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[S] re: Mapping a character string into an object

daemon@ATHENA.MIT.EDU (fan@katan.cybercom.net)
Thu Aug 5 10:36:26 1999

From: fan@katan.cybercom.net
Date: Thu, 5 Aug 1999 10:33:09 -0400 (EDT)
To: s-news@wubios.wustl.edu
Message-Id: <Pine.LNX.4.04.9908051030090.26733-100000@katan.cybercom.net>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


Upon respondents's suggestions, get() and paste() 
get the work done. I was not not aware of the "get" function.
Thanks- Fan

-----Original Message-----
From: fan@katan.cybercom.net [mailto:fan@katan.cybercom.net]
Sent: Wednesday, August 04, 1999 9:49 PM
To: s-news@wubios.wustl.edu
Subject: [S] Mapping a character string into an object


I am working on producing a table of N rows. Each row contains
summaries for a different name, say "A", "B", ...
For each name, there are multiple data vectors corresponding to it.

Then, I apply some operations for these names, one at a time.
I am considering using a loop, so that codes can be
reused. In an attempt, I made a list:

namelist <- c("A", "B", ...)

The job I am thinking about has a diagram as:

for (i in 1:length(namelist))
{
        # call the variable named "namelist[i]" for computation.
        # this requires "a map from a string to an object"

        # An example is:
        # cat(a <- mean(*.c),"\t", b<-var(*.d), where * is the ith element
of
        # namelist.
}

I don't know of a way to refer to different objects from within a loop
as iterator i changes. Please send in your ideas.

The reasons that I didn't combine all the data vectors into a big
matrix/array and then refer it via index are:

  1.duplicating data is consuming, especially when the dataset is large.
  2.multiple data-vectors for a certain name (e.g., A.c, A.d, A.e) may




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