[GRASS-user] Call an external function from GRASS-Pythons Scripts

Kim_Besson1 · April 22, 2010, 9:02am

Hi

I’m developing a small GRASS Python script but I will need to call an external executive. I already know where to put it (at $PATH) but i don’t know how to call it from Python GRASS Script. How can I do this? (as an example it’s helloWorld )

Thanks
Best regards
Kim

martinl · April 22, 2010, 10:12am

Hi,

2010/4/22 Kim Besson <kimbesson1981@gmail.com>:

I'm developing a small GRASS Python script but I will need to call an
external executive. I already know where to put it (at $PATH) but i don't
know how to call it from Python GRASS Script. How can I do this? (as an
example it's helloWorld )

grass.call()

e.g.

grass.call(['whoami', '--version'])

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

martinl · April 22, 2010, 11:36am

Hi,

2010/4/22 Kim Besson <kimbesson1981@gmail.com>:

From http://download.osgeo.org/grass/grass6_progman/core_8py_source.html I
see that besides the main argument there is **kwargs. What is this?

all defined arguments from Popen

http://download.osgeo.org/grass/grass6_progman/classpython_1_1core_1_1Popen.html

Martin
--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

martinl · April 22, 2010, 11:52am

Hi,

{please keep discussion on ML}

2010/4/22 Kim Besson <kimbesson1981@gmail.com>:

Bur for instance you separated two argument inside . This means that for
instance If I need to call a external function and inser input and output I
would have to do this:
grass.call(['whoami', 'input_file', 'output_file']) or
grass.call(['whoami input output_file'])

it's first argument 'args'.

Martin

PS: Probably it would be reasonable to change configuration of ML
(send replay to the list instead to 'from') to avoid this mistake.

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

Kim_Besson1 · April 22, 2010, 11:56am

Here now at the ML for everyone
But which one of the two options is correct? The first one or the second one? Or both are ok? (at least the second one is correct I suppose)

2010/4/22 Martin Landa <landa.martin@gmail.com>

Hi,

{please keep discussion on ML}

2010/4/22 Kim Besson <kimbesson1981@gmail.com>:

Bur for instance you separated two argument inside . This means that for
instance If I need to call a external function and inser input and output I
would have to do this:
grass.call([‘whoami’, ‘input_file’, ‘output_file’]) or
grass.call([‘whoami input output_file’])

it’s first argument ‘args’.

Martin

PS: Probably it would be reasonable to change configuration of ML
(send replay to the list instead to ‘from’) to avoid this mistake.

–

Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

martinl · April 22, 2010, 12:18pm

Hi,

2010/4/22 Kim Besson <kimbesson1981@gmail.com>:

> would have to do this:
> grass.call(['whoami', 'input_file', 'output_file']) or
> grass.call(['whoami input output_file'])

if the syntax is 'cmd input output' then

grass.call(['cmd', 'input', 'output'])

see

http://docs.python.org/library/subprocess.html#subprocess.Popen

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

martinl · April 22, 2010, 12:21pm

Hi,

2010/4/22 Martin Landa <landa.martin@gmail.com>:

> would have to do this:
> grass.call(['whoami', 'input_file', 'output_file']) or
> grass.call(['whoami input output_file'])

if the syntax is 'cmd input output' then

grass.call(['cmd', 'input', 'output'])

see

http://docs.python.org/library/subprocess.html#subprocess.Popen

or check existing GRASS scripts, e.g.

http://trac.osgeo.org/grass/browser/grass/trunk/scripts/v.in.e00/v.in.e00.py#L135

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

neteler · April 22, 2010, 1:36pm

On Thu, Apr 22, 2010 at 1:52 PM, Martin Landa <landa.martin@gmail.com> wrote:
...

PS: Probably it would be reasonable to change configuration of ML
(send replay to the list instead to 'from') to avoid this mistake.

Hi Martin,

I would strongly advise against that (see '90s archive for some damages
and OSGeo list archive too and others):

http://www.unicom.com/pw/reply-to-harmful.html
http://woozle.org/~neale/papers/reply-to-still-harmful.html

It is too risky. I have been asked several times in the past to remove
posting from a list archive which is not only a PITA but also a can
or worms (think censorship; which message to delete, which not etc.).

My strong 0.02 cents
Markus

Nikos_Alexandris1 · May 5, 2010, 3:30am

On Thu, Apr 22, 2010 at 1:52 PM, Martin Landa <landa.martin@gmail.com> wrote:
...

> PS: Probably it would be reasonable to change configuration of ML
> (send replay to the list instead to 'from') to avoid this mistake.

On Thursday 22 of April 2010 15:36:37 Markus Neteler wrote:

Hi Martin,

I would strongly advise against that (see '90s archive for some damages
and OSGeo list archive too and others):

http://www.unicom.com/pw/reply-to-harmful.html
http://woozle.org/~neale/papers/reply-to-still-harmful.html

It is too risky. I have been asked several times in the past to remove
posting from a list archive which is not only a PITA but also a can
or worms (think censorship; which message to delete, which not etc.).

My strong 0.02 cents
Markus

Markus,

I just read about this past debate. So, it is always better to use the "Reply
to Mailing-List" button (KMail here)?

Pohhh... I am really sorry if I caused any problem since I've always been
using the "Reply-to-All" for the list and the "Reply-to" for personal
messages.

Nikos

martinl · May 5, 2010, 2:29pm

Hi,

2010/5/5 Nikos Alexandris <nikos.alexandris@felis.uni-freiburg.de>:

[...]

I just read about this past debate. So, it is always better to use the "Reply
to Mailing-List" button (KMail here)?

Pohhh... I am really sorry if I caused any problem since I've always been
using the "Reply-to-All" for the list and the "Reply-to" for personal
messages.

AFAIU, "Reply-to-All" is OK.

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

neteler · May 6, 2010, 7:37pm

On Wed, May 5, 2010 at 5:30 AM, Nikos Alexandris
<nikos.alexandris@felis.uni-freiburg.de> wrote:

On Thu, Apr 22, 2010 at 1:52 PM, Martin Landa <landa.martin@gmail.com> wrote:
...

> PS: Probably it would be reasonable to change configuration of ML
> (send replay to the list instead to 'from') to avoid this mistake.

On Thursday 22 of April 2010 15:36:37 Markus Neteler wrote:

Hi Martin,

I would strongly advise against that (see '90s archive for some damages
and OSGeo list archive too and others):

http://www.unicom.com/pw/reply-to-harmful.html
http://woozle.org/~neale/papers/reply-to-still-harmful.html

It is too risky. I have been asked several times in the past to remove
posting from a list archive which is not only a PITA but also a can
or worms (think censorship; which message to delete, which not etc.).

My strong 0.02 cents
Markus

Markus,

I just read about this past debate. So, it is always better to use the "Reply
to Mailing-List" button (KMail here)?

I don't know such button... (no KMail knowledge).

Pohhh... I am really sorry if I caused any problem since I've always been
using the "Reply-to-All" for the list and the "Reply-to" for personal
messages.

But "Reply-to-All" for the list and the "Reply-to" for personal messages
is perfect! Just go on. Nothing changed. I suggested to not change anything

Markus

Nikos_Alexandris1 · May 17, 2010, 11:14pm

Martin Landa:
...

>> > PS: Probably it would be reasonable to change configuration of ML
>> > (send replay to the list instead to 'from') to avoid this mistake.

Markus Neteler:

>> I would strongly advise against that (see '90s archive for some damages
>> and OSGeo list archive too and others):
>>
>> http://www.unicom.com/pw/reply-to-harmful.html
>> http://woozle.org/~neale/papers/reply-to-still-harmful.html
>>
>> It is too risky. I have been asked several times in the past to remove
>> posting from a list archive which is not only a PITA but also a can
>> or worms (think censorship; which message to delete, which not etc.).

Nikos Alexandris

> I just read about this past debate. So, it is always better to use the
> "Reply to Mailing-List" button (KMail here)?

Markus Neteler:

I don't know such button... (no KMail knowledge).

Nikos Alexandris:

> Pohhh... I am really sorry if I caused any problem since I've always been
> using the "Reply-to-All" for the list and the "Reply-to" for personal
> messages.

Markus Neteler wrote:

But "Reply-to-All" for the list and the "Reply-to" for personal messages
is perfect! Just go on. Nothing changed. I suggested to not change anything

Nothing important, just for the records.

Reading (again) this thread: I extracted from the respective "debate" (I mean
the links posted by MarkusN [1][2]) that the "Reply to Mailing-List" button
(at least in KMail) adds some "special" header or something like that which is
the correct way to _reply_ in the list.

In addition, in the past I had asked Markus to remove some posts of mine (due
to a silly mistake) which was a really time-consuming and difficult process
(judging by Markus replies back then -- but I am so grateful he helped me out
-- thanks again Markus).

So, I felt for a moment bad thinking that I could have brought even more
problems in the list. Nevermind, it is good to know that there are no problems
using the Reply-to-All button.

Nikos

---
[1] <http://www.unicom.com/pw/reply-to-harmful.html>
[2] <http://woozle.org/~neale/papers/reply-to-still-harmful.html>