how to change the class of a group of objects

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Ben Mazzotta
Sent: Monday, November 23, 2009 4:51 PM
To: r-help at r-project.org
Subject: [R] how to change the class of a group of objects

Dear R users,

I would like to change the class of a group of objects in R memory from
"numeric" to "dist". I can manipulate the class using

class(foo) <- bar

but I cannot get the same command to work on groups of variables. When I
use for() loops and lists of names, inevitably I have to specify

class(get("foo")) <- bar

which causes class() to return an error. Could anyone offer some advice
how to manipulate classes and attributes of a list of objects in memory?

Many thanks,
Ben




a <- c(1:5)
b <- c(1:10)
c <- c(1:20)

# What I would like to do is coerce all of these to class "dist".
# How can I write a command that changes the class of a, b, AND c to
"dist"?
# Most of my answers include a list or a for() loop over (a, b, c)
# How can I write a command that changes attributes of a, b, and c all
at the same time?
# I can force the process to work for a few objects, but it is
time-consuming.
# For reference, I am including the following commands.

class(a)
class(get(letters[1]))
class(a) <- "dist"
class(a) <- NULL
class(a)
class(get(letters[1])) <- "dist"


--
Ben Mazzotta
PhD Candidate
Fletcher School, Tufts University
160 Packard Ave, Medford MA 02155
benjamin.mazzotta at tufts.edu
+1.617.462.4486

Dear R users,

I would like to change the class of a group of objects in R memory from
"numeric" to "dist". I can manipulate the class using

class(foo) <- bar

but I cannot get the same command to work on groups of variables. When I
use for() loops and lists of names, inevitably I have to specify

class(get("foo")) <- bar

which causes class() to return an error. Could anyone offer some advice
how to manipulate classes and attributes of a list of objects in memory?

Many thanks,
Ben




a <- c(1:5)
b <- c(1:10)
c <- c(1:20)

# What I would like to do is coerce all of these to class "dist".
# How can I write a command that changes the class of a, b, AND c to
"dist"?
# Most of my answers include a list or a for() loop over (a, b, c)
# How can I write a command that changes attributes of a, b, and c all
at the same time?
# I can force the process to work for a few objects, but it is
time-consuming.
# For reference, I am including the following commands.

class(a)
class(get(letters[1]))
class(a) <- "dist"
class(a) <- NULL
class(a)
class(get(letters[1])) <- "dist"


--
Ben Mazzotta
PhD Candidate
Fletcher School, Tufts University
160 Packard Ave, Medford MA 02155
benjamin.mazzotta at tufts.edu
+1.617.462.4486

Ben, 

In general, when you define a, b, and c as below, the c() wrapper is not needed, since the : operator returns a vector anyway.  Also, best not to name variables 'c' to avoid confusion with the function you're using. 

Regarding your actual question, lapply(list(a, b, c), "class<-", "dist") might work, but your objects in your example don't seem to be able to be coerced to dist objects.  E.g., as.dist(b) gives an error.  If you have data that can actually work as dist objects, you might try the above line though.

Erik  

  

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Ben Mazzotta
Sent: Monday, November 23, 2009 4:51 PM
To: r-help at r-project.org
Subject: [R] how to change the class of a group of objects

Dear R users,

I would like to change the class of a group of objects in R memory from
"numeric" to "dist". I can manipulate the class using

class(foo) <- bar

but I cannot get the same command to work on groups of variables. When I
use for() loops and lists of names, inevitably I have to specify

class(get("foo")) <- bar

which causes class() to return an error. Could anyone offer some advice
how to manipulate classes and attributes of a list of objects in memory?

Many thanks,
Ben




a <- c(1:5)
b <- c(1:10)
c <- c(1:20)

# What I would like to do is coerce all of these to class "dist".
# How can I write a command that changes the class of a, b, AND c to
"dist"?
# Most of my answers include a list or a for() loop over (a, b, c)
# How can I write a command that changes attributes of a, b, and c all
at the same time?
# I can force the process to work for a few objects, but it is
time-consuming.
# For reference, I am including the following commands.

class(a)
class(get(letters[1]))
class(a) <- "dist"
class(a) <- NULL
class(a)
class(get(letters[1])) <- "dist"


--
Ben Mazzotta
PhD Candidate
Fletcher School, Tufts University