R help - Aug 2009 - how to get R interpreter to remember constant values without using any memory location

Maybe I expect too much from a non compiled language.
Anyway, I wonder whether it is possible in R to set constant values without
using any memory location that would take useless space
bacause such values are not going to be changed along the program. It's just
a way to assign a mnemnic name tos some constant values.
For instance, I would like R interpreter to replace all occurrences of mnemonic
"Monday" with the number 1, "Tuesday"  with the number 2,
"Wednesday  with the number 3, and so on ...  without having to assign such
values to memory locations.
Maybe environment variables are the way to go ?  

Thank you in advance for your advice,
Maura




tutti i telefonini TIM!


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On Thu, Aug 13, 2009 at 04:05:07PM +0200, mauede at alice.it
wrote:
> Maybe I expect too much from a non compiled language.
> Anyway, I wonder whether it is possible in R to set constant values
> without using any memory location that would take useless space
> bacause such values are not going to be changed along the program.
If not in memory, where would the data live? None of the compiled or
interpreted languages I have come accross implement magic.

cu
	Philipp

-- 
Dr. Philipp Pagel
Lehrstuhl f?r Genomorientierte Bioinformatik
Technische Universit?t M?nchen
Wissenschaftszentrum Weihenstephan
85350 Freising, Germany
http://webclu.bio.wzw.tum.de/~pagel/

mauede wrote:
> 
> Maybe I expect too much from a non compiled language.
> Anyway, I wonder whether it is possible in R to set constant values
> without using any memory location that would take useless space 
> bacause such values are not going to be changed along the program. It's
> just a way to assign a mnemnic name tos some constant values.
> For instance, I would like R interpreter to replace all occurrences of
> mnemonic "Monday" with the number 1, "Tuesday"  with
the number 2,
> "Wednesday  with the number 3, and so on ...  without having to assign
> such values to memory locations.
> Maybe environment variables are the way to go ?  
> 
> 
  It would help if you were a little bit more specific about what you wanted
to do and why.
My initial reaction is that this is exactly the thing that the
"factor"
class in R is designed
to do -- maintain a list of unique names corresponding to integer codes, and
handle
them (almost) transparently.  (There are a few tricky aspects to dealing
safely/correctly
with factor conversions: see
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-factors:factors )

  Ben Bolker
-- 
View this message in context:
http://www.nabble.com/how-to-get-R-interpreter-to-remember-constant-values-without-using-any-memory-location-tp24955624p24956298.html
Sent from the R help mailing list archive at Nabble.com.

mauede wrote:
> 
> Maybe I expect too much from a non compiled language.
> Anyway, I wonder whether it is possible in R to set constant values
> without using any memory location that would take useless space 
> bacause such values are not going to be changed along the program. It's
> just a way to assign a mnemnic name tos some constant values.
> For instance, I would like R interpreter to replace all occurrences of
> mnemonic "Monday" with the number 1, "Tuesday"  with
the number 2,
> "Wednesday  with the number 3, and so on ...  without having to assign
> such values to memory locations.
> Maybe environment variables are the way to go ?  
> 
> 
  It would help if you were a little bit more specific about what you wanted
to do and why.
My initial reaction is that this is exactly the thing that the
"factor"
class in R is designed
to do -- maintain a list of unique names corresponding to integer codes, and
handle
them (almost) transparently.  (There are a few tricky aspects to dealing
safely/correctly
with factor conversions: see
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-factors:factors )

  Ben Bolker
-- 
View this message in context:
http://www.nabble.com/how-to-get-R-interpreter-to-remember-constant-values-without-using-any-memory-location-tp24955624p24956310.html
Sent from the R help mailing list archive at Nabble.com.

mauede wrote:
> 
> Maybe I expect too much from a non compiled language.
> Anyway, I wonder whether it is possible in R to set constant values
> without using any memory location that would take useless space 
> bacause such values are not going to be changed along the program. It's
> just a way to assign a mnemnic name tos some constant values.
> For instance, I would like R interpreter to replace all occurrences of
> mnemonic "Monday" with the number 1, "Tuesday"  with
the number 2,
> "Wednesday  with the number 3, and so on ...  without having to assign
> such values to memory locations.
> Maybe environment variables are the way to go ?  
> 
> 
  It would help if you were a little bit more specific about what you wanted
to do and why.
My initial reaction is that this is exactly the thing that the
"factor"
class in R is designed
to do -- maintain a list of unique names corresponding to integer codes, and
handle
them (almost) transparently.  (There are a few tricky aspects to dealing
safely/correctly
with factor conversions: see
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-factors:factors )

  Ben Bolker
-- 
View this message in context:
http://www.nabble.com/how-to-get-R-interpreter-to-remember-constant-values-without-using-any-memory-location-tp24955624p24956333.html
Sent from the R help mailing list archive at Nabble.com.

mauede wrote:
> 
> Maybe I expect too much from a non compiled language.
> Anyway, I wonder whether it is possible in R to set constant values
> without using any memory location that would take useless space 
> bacause such values are not going to be changed along the program. It's
> just a way to assign a mnemnic name tos some constant values.
> For instance, I would like R interpreter to replace all occurrences of
> mnemonic "Monday" with the number 1, "Tuesday"  with
the number 2,
> "Wednesday  with the number 3, and so on ...  without having to assign
> such values to memory locations.
> Maybe environment variables are the way to go ?  
> 
> 
  It would help if you were a little bit more specific about what you wanted
to do and why.
My initial reaction is that this is exactly the thing that the
"factor"
class in R is designed
to do -- maintain a list of unique names corresponding to integer codes, and
handle
them (almost) transparently.  (There are a few tricky aspects to dealing
safely/correctly
with factor conversions: see
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-factors:factors )

  Ben Bolker
-- 
View this message in context:
http://www.nabble.com/how-to-get-R-interpreter-to-remember-constant-values-without-using-any-memory-location-tp24955624p24956351.html
Sent from the R help mailing list archive at Nabble.com.

Like Ben, I wonder what the reason for doing this is.

First of all, the amount of memory indicated by your example is so 
small I can't imagine it would make any difference. If you have such 
a large number of values that the amount of memory is significant -- 
and store them somewhere that isn't in memory (such as physical disk 
memory), then reading them into memory when you need to use them 
might affect performance a lot.

Environment variables use memory also -- it's just someone else's 
memory (the OS instead of R).

-Don

At 4:05 PM +0200 8/13/09, <mauede at alice.it>
wrote:
>Maybe I expect too much from a non compiled language.
>Anyway, I wonder whether it is possible in R to set constant values 
>without using any memory location that would take useless space
>bacause such values are not going to be changed along the program. 
>It's just a way to assign a mnemnic name tos some constant values.
>For instance, I would like R interpreter to replace all occurrences 
>of mnemonic "Monday" with the number 1, "Tuesday"  with
the number
>2, "Wednesday  with the number 3, and so on ...  without having to 
>assign such values to memory locations.
>Maybe environment variables are the way to go ? 
>
>Thank you in advance for your advice,
>Maura
>
>
>
>
>tutti i telefonini TIM!
>
>
>	[[alternative HTML version deleted]]
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062