[R] Taking code from packages

Ales Ziberna aleszib at gmail.com
Fri Jan 13 14:15:43 CET 2006

First thank you for you reply!

First let me assure you that I did not think or intent to just use their 
code and use GPL as an excuse.

Although I would like to just make my package dependant on theirs and use 
their functions that is not possible. The main reason is that I do not want 
to use the whole functions, but just parts of it. For example, I only need 
one statistics, while their function computes several. Since I call my 
function several thousand times, I want to make it as fast as possible.

I am also modified (although only slightly) the functions, I am a little 
worried about naming them as sole authors of the function, since I do not 
want to make them responsible for any mistakes I have made.

What I was thinking of doing is:

  1.. Notify the original authors!
  2.. In the Author (s) section of the function help, I would write "Their 
name (Modifications made by My Name").
  3.. Use the same license (GPL 2) as they do.

I did not intent to write them as the package authors, since their code 
represent a very small part of the whole package.

How does that sound?

Best regards,

Ales Ziberna

P.S.: I did not find any other special copyright notices.

----- Original Message ----- 
From: "Duncan Murdoch" <murdoch at stats.uwo.ca>
To: "Ales Ziberna" <aleszib at gmail.com>
Cc: <r-help at stat.math.ethz.ch>
Sent: Friday, January 13, 2006 1:46 PM
Subject: Re: [R] Taking code from packages

On 1/13/2006 2:04 AM, Ales Ziberna wrote:
> Hello!
> I am currently in the process of creating (my first) package, which (when
> ready) I intend to publish to CRAN. In the process of creating this 
> package
> I have taken some code form existing packages. I have actually copied 
> parts
> of functions in to new functions. This code is usually something very 
> basic
> such as Rand index. What is the proper procedure for this?
> Since most of R (and also the packages I have taken code form) is 
> published
> under GPL, I think this should be OK. However I do not know if:
> 1. I should still ask authors of the packages for permission or at
> least notify them.

It is polite to notify them.

> 2. Ad references to the functions (and packages) from which I had taken
> the code or only to the references they use.

The GPL requires that you maintain their copyright notices.  You have
the right to use their work, the GPL doesn't give you ownership of it.
The usual way to do this is to leave their copyright notice intact, and
add your own if you have made modifications.

An alternative which is usually (but not always) better is to say that
your package depends on theirs, and then just use their functions.  The
advantage is that it avoids any of the above mixed copyright issues, and
it makes sure that when the author fixes a bug, you benefit too.  The
disadvantage is that it makes your package dependent on theirs, so if
changes are needed in it for some future version of R, you'll have to
wait for the other maintainer to do them (or copy their code at that point).

(I'm a little sensitive about dependencies now, since the LaTeX seminar
template I've used a few times no longer works.  It depends on too many
LaTeX packages, and someone, somewhere has introduced incompatibilities
in them.  Seems like I'll be forced to use Powerpoint or Impress.)

Duncan Murdoch

> What about regarding code that was sent to the list, usually as a response
> to one of my problems. I assume that in this case it is best to consult 
> the
> author?

> Any comments and opinions are very welcomed!
> Best regards,
> Ales Ziberna
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