[R] Re use objects from within a custom made function
Hi everyone,
i'm having a problem extracting objects out of functions i've created, so i
can use them for further analysis. Here's a small example:
# ---
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(x,y,z)
}
# ---
This returns the 3 objects as $x, $y and $z. I cannot, however, access these
objects individually by typing for example:
test$x
I know i can do this by adding an extra arrow head to the assignment arrow
(-), but I am sure that is not how it is done in some of the established R
functions (like when calling lm$coef out of the lm function). Is there a
simple command i've omitted from the function that allows access to objects
inside it?
Thanks in advance,
Steve
--
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Re: [R] Re use objects from within a custom made function
test$x doesn't evaluate the function, you want something like test(1,2)$x, e.g.:
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(list(x=x,y=y,z=z))
}
test(1,2)$x
[1] 1 2
test(1,2)$y
[1] 2
test(1,2)$z
[1] 0.5
Or if you want to avoid evaluating your function multiple times:
res - test(1,2)
res$x
[1] 1 2
res$y
[1] 2
res$z
[1] 0.5
res
$x
[1] 1 2
$y
[1] 2
$z
[1] 0.5
Stropharia wrote:
Hi everyone,
i'm having a problem extracting objects out of functions i've created, so i
can use them for further analysis. Here's a small example:
# ---
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(x,y,z)
}
# ---
This returns the 3 objects as $x, $y and $z. I cannot, however, access these
objects individually by typing for example:
test$x
I know i can do this by adding an extra arrow head to the assignment arrow
(-), but I am sure that is not how it is done in some of the established R
functions (like when calling lm$coef out of the lm function). Is there a
simple command i've omitted from the function that allows access to objects
inside it?
Thanks in advance,
Steve
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] Re use objects from within a custom made function
-Original Message-
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of Stropharia
Sent: Monday, October 12, 2009 4:07 PM
To: r-help@r-project.org
Subject: [R] Re use objects from within a custom made function
Hi everyone,
i'm having a problem extracting objects out of functions i've
created, so i
can use them for further analysis. Here's a small example:
# ---
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(x,y,z)
}
# ---
This returns the 3 objects as $x, $y and $z. I cannot,
however, access these
objects individually by typing for example:
test$x
I know i can do this by adding an extra arrow head to the
assignment arrow
(-), but I am sure that is not how it is done in some of
the established R
functions (like when calling lm$coef out of the lm function).
Is there a
simple command i've omitted from the function that allows
access to objects
inside it?
Thanks in advance,
Steve
--
Steve,
I see a couple of problems (at least from my perspective). If you ever got
your function to run, you would see a warning stating that returning
multiple objects is deprecated. In your example of using the function, you
don't call it with any parameters, and the definition has no default values.
I also would be inclined to assign the results of the function call to a
variable/object and access the values from there.
So I would approach your problem as follows:
test - function(i, j){
x - i:j
y - i*j
z - i/j
list(x=x, y=y, z=z)
}
my.result - test(1,4)
my.result$x
[1] 1 2 3 4
If you don't want to assign the output of test() to an object, then you will
need to do something like
test(1,4)$x
But this is inefficient because each time you access one of the components,
you need to rerun the function.
Hope this is helpful,
Dan
Daniel Nordlund
Bothell, WA USA
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Re: [R] Re use objects from within a custom made function
Thanks a lot Tony and Daniel for making that clear.
best,
Steve
Stropharia wrote:
Hi everyone,
i'm having a problem extracting objects out of functions i've created, so
i can use them for further analysis. Here's a small example:
# ---
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(x,y,z)
}
# ---
This returns the 3 objects as $x, $y and $z. I cannot, however, access
these objects individually by typing for example:
test$x
I know i can do this by adding an extra arrow head to the assignment arrow
(-), but I am sure that is not how it is done in some of the established
R functions (like when calling lm$coef out of the lm function). Is there a
simple command i've omitted from the function that allows access to
objects inside it?
Thanks in advance,
Steve
--
View this message in context:
http://www.nabble.com/Reuse-objects-from-within-a-custom-made-function-tp25864695p25866081.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] Re use objects from within a custom made function
On Oct 12, 2009, at 7:06 PM, Stropharia wrote:
Hi everyone,
i'm having a problem extracting objects out of functions i've
created, so i
can use them for further analysis. Here's a small example:
# ---
test - function(i, j){
x - i:j
y - i*j
z - i/j
return(x,y,z)
}
# ---
This returns the 3 objects as $x, $y and $z. I cannot, however,
access these
objects individually by typing for example:
test$x
Generally one assigns the resutlts of a function to an object name:
ll - test(1,2)
Warning message:
In return(x, y, z) : multi-argument returns are deprecated
ll
$x
[1] 1 2
$y
[1] 2
$z
[1] 0.5
str(ll)
List of 3
$ x: int [1:2] 1 2
$ y: num 2
$ z: num 0.5
So you would not get the warnings if you instead ended the function
with:
return(list(x,y,z) )
I know i can do this by adding an extra arrow head to the assignment
arrow
(-), but I am sure that is not how it is done in some of the
established R
functions (like when calling lm$coef out of the lm function). Is
there a
simple command i've omitted from the function that allows access to
objects
inside it?
Thanks in advance,
Steve
--
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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and provide commented, minimal, self-contained, reproducible code.
