using reserved words in R, and reuse variable names in different functions

Hi list,
I am writing several functions and running out variable names.  I am using
words such as "t", "c", "matrix" to keep the notation same as formulas I am
using.

For example I have,

unnormalized <- function(t, x, y){
   val <- rnorm(t, mean=x, var=y)
   return(val)
}

metropolis <- function(t, c, x, y){
   den1 <- unnormalized(t, mean=x, sd=y)
   den2 <- unnormalized(c, mean=x, sd=y)
   if(den1 < den2)
      return(a)
   else
      return(b)
}

for(i in 1: 100){
   matrix <- c()
   matrix[i] <- metroplis(1, 2, 3, 4)
}
Here, I reused letter "t" and "c", and the word "matrix".  Could this cause
any potential problems?

Thanks, that was just an example I came up with.  I was just curious if
using same variable names in different functions would cause problems.

 Especially with reserved words.

Mike

On Fri, Mar 1, 2013 at 5:45 PM, David Winsemius <dwinsemius at comcast.net>wrote:

On Mar 1, 2013, at 1:56 PM, C W wrote:

Hi list,
I am writing several functions and running out variable names.  I am

using

words such as "t", "c", "matrix" to keep the notation same as formulas I

am

using.

For example I have,

unnormalized <- function(t, x, y){
   val <- rnorm(t, mean=x, var=y)
   return(val)
}

metropolis <- function(t, c, x, y){
   den1 <- unnormalized(t, mean=x, sd=y)
   den2 <- unnormalized(c, mean=x, sd=y)
   if(den1 < den2)
      return(a)
   else
      return(b)
}

for(i in 1: 100){
   matrix <- c()
   matrix[i] <- metroplis(1, 2, 3, 4)
}
Here, I reused letter "t" and "c", and the word "matrix".  Could this

cause

any potential problems?

 Whatever problems you are having at the moment (and they appear to be
many) are not  due to using existing function names as data-object names.
You are asked to report the error messages you get with your code problems,
and those messages I found to be reasonably informative for the first 5
errors I found.

See fortune("dog").

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of Rolf Turner
Sent: Saturday, March 02, 2013 5:01 AM
To: Sarah Goslee
Cc: r-help
Subject: Re: [R] using reserved words in R, and reuse variable names in different
functions

On 03/02/2013 01:12 PM, Sarah Goslee wrote:

On Fri, Mar 1, 2013 at 7:06 PM, C W <tmrsg11 at gmail.com> wrote:

Thanks, that was just an example I came up with.  I was just curious if
using same variable names in different functions would cause problems.

No. The environment of a function is independent of other functions.

  Especially with reserved words.

Yes. Using reserved words can cause all kinds of subtle problems. Avoid it.

Very sound advice.  But it should be noted that "t", "c", and "matrix"
to which
the OP referred are *not* technically reserved words.  Nonetheless their use
as names of user-defined objects should be eschewed.  See fortune("dog").

You *can't* actually assign values to reserved words.  E.g.

     TRUE <- 42

throws an error.  (Whereas matrix <- 42, bad form though it may be,
does not throw an error.)

     cheers,

         Rolf Turner

Thanks, everyone, I will definitely avoid it.  Is there any tips on naming
variables?  I've seen the Google R style guider and Hadley R style guide.

For example, I want to use pie_t, to denote stationary distribution pie at
time t.  Both "pi" and "pie" are function names themselves.

Mike

On Fri, Mar 1, 2013 at 8:12 PM, William Dunlap <wdunlap at tibco.com> wrote:

See fortune("dog").

To wit:
   "Firstly, don't call your matrix 'matrix'. Would you call your dog
'dog'? Anyway, it might clash with the function 'matrix'"

I once had a cat named "kitty" and she never had a problem with it.

Clashes between non-functions and functions that cause problems are not
that common.  With 4000 packages, each with a number of functions, it is
hard to avoid using a name that someone has used for a function.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]

On Behalf

Of Rolf Turner
Sent: Saturday, March 02, 2013 5:01 AM
To: Sarah Goslee
Cc: r-help
Subject: Re: [R] using reserved words in R, and reuse variable names in

different

functions

On 03/02/2013 01:12 PM, Sarah Goslee wrote:

On Fri, Mar 1, 2013 at 7:06 PM, C W <tmrsg11 at gmail.com> wrote:

Thanks, that was just an example I came up with.  I was just curious

if

using same variable names in different functions would cause problems.

No. The environment of a function is independent of other functions.

   Especially with reserved words.

Yes. Using reserved words can cause all kinds of subtle problems.

Avoid it.

Very sound advice.  But it should be noted that "t", "c", and "matrix"
to which
the OP referred are *not* technically reserved words.  Nonetheless their

use

as names of user-defined objects should be eschewed.  See fortune("dog").

You *can't* actually assign values to reserved words.  E.g.

      TRUE <- 42

throws an error.  (Whereas matrix <- 42, bad form though it may be,
does not throw an error.)

      cheers,

          Rolf Turner

	[[alternative HTML version deleted]]

On Fri, Mar 1, 2013 at 7:06 PM, C W <tmrsg11 at gmail.com> wrote:

Thanks, that was just an example I came up with.  I was just curious if
using same variable names in different functions would cause problems.

No. The environment of a function is independent of other functions.

  Especially with reserved words.

Yes. Using reserved words can cause all kinds of subtle problems. Avoid it.

On 13-03-01 8:35 PM, C W wrote:

pie is a function, but all it does is draw pie charts, so who cares if
you mask it? :-).

Duncan Murdoch

Duncan's comment may not qualify as a fortune, but it did make
me chuckle.

Peter Ehlers

On 2013-03-02 03:01, Duncan Murdoch wrote:

On 13-03-01 8:35 PM, C W wrote:

[...snip...]

pie is a function, but all it does is draw pie charts, so who cares if
you mask it? :-).

Duncan Murdoch

[...snip...]