R help - Aug 2005 - how to use the function from another package

Hi, I am trying to write a package(A) for myself and need to use a
function from another package(B) which is in R already(need to install
it before use). Could anyone tell me how to implement that? Also I
hope that my package gives an ERROR message(something like "STOP,
please install package B first") if the package B is not installed
yet.  It is my first time to write a package. Thanks very much for
your help.

Peter

See "Writing R Extensions" / Creating R package / Description file /
"depends" field (section 1.1.1).

Jarek
====================================================\======
 Jarek Tuszynski, PhD.                           o / \ 
 Science Applications International Corporation  <\__,|  
 (703) 676-4192                                   ">   \
 Jaroslaw.W.Tuszynski at saic.com                     `    \



-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Peter Yang
Sent: Tuesday, August 09, 2005 1:56 PM
To: R-help at stat.math.ethz.ch
Subject: [R] how to use the function from another package

Hi, I am trying to write a package(A) for myself and need to use a function
from another package(B) which is in R already(need to install it before
use). Could anyone tell me how to implement that? Also I hope that my
package gives an ERROR message(something like "STOP, please install package
B first") if the package B is not installed yet.  It is my first time to
write a package. Thanks very much for your help.

Peter

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R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
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On Tue, 9 Aug 2005, Peter Yang wrote:
> I am trying to write a package(A) for myself and need to use a
> function from another package(B) which is in R already(need to install
> it before use). Could anyone tell me how to implement that? Also I
> hope that my package gives an ERROR message(something like "STOP,
> please install package B first") if the package B is not installed
> yet.  It is my first time to write a package. Thanks very much for
> your help.
In your package's DESCRIPTION file, you should have an entry
that lists your package dependencies. Simply add the other
package there as well.

For example, to support the current version of R and a
package named foo, the entry would look like this:

    Depends: R (>= 2.1.1), foo

----------------------------------------------------------
SIGSIG -- signature too long (core dumped)

> Thanks very much for your help. Do I still have to write library( ) to
load the library in my code after I add a "depends" field in the
DESCRIPTION
file? 

No, 

First when user of your package downloads it (at least on Windows machines)
all required packages are also downloaded (this mechanism sometimes needs
manual help, but that is another story). Then when he loads your package (by
calling library(YourPackage)) all required packages are loaded into R.

One good way to research this kind of questions (other than documentation
and R-Help) is to study source code of other people packages.
   
Jarek
====================================================\======
 Jarek Tuszynski, PhD.                           o / \ 
 Science Applications International Corporation  <\__,|  
 (703) 676-4192                                   ">   \
 Jaroslaw.W.Tuszynski at saic.com                     `    \


-----Original Message-----
From: peterwyang at gmail.com [mailto:peterwyang at gmail.com] 
Sent: Tuesday, August 09, 2005 2:57 PM
To: Tuszynski, Jaroslaw W.
Subject: Re: [R] how to use the function from another package

Thanks very much for your help. Do I still have to write library( ) to load
the library in my code after I add a "depends" field in the
DESCRIPTION
file? Thanks.

Peter


On 8/9/05, Tuszynski, Jaroslaw W. <JAROSLAW.W.TUSZYNSKI at saic.com>
wrote:
> See "Writing R Extensions" / Creating R package / Description
file /
> "depends" field (section 1.1.1).
> 
> Jarek
> ====================================================\======> 
>  Jarek Tuszynski, PhD.                           o / \
>  Science Applications International Corporation  <\__,|
>  (703) 676-4192                                   ">   \
>  Jaroslaw.W.Tuszynski at saic.com                     `    \
> 
> 
> 
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Peter Yang
> Sent: Tuesday, August 09, 2005 1:56 PM
> To: R-help at stat.math.ethz.ch
> Subject: [R] how to use the function from another package
> 
> Hi, I am trying to write a package(A) for myself and need to use a 
> function from another package(B) which is in R already(need to install 
> it before use). Could anyone tell me how to implement that? Also I 
> hope that my package gives an ERROR message(something like "STOP, 
> please install package B first") if the package B is not installed 
> yet.  It is my first time to write a package. Thanks very much for your
help.
> 
> Peter
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>