[Qgis-user] different QGIS behavior between windows and lubuntu

Fri May 29 14:16:37 PDT 2015

On Fri, 29 May 2015 16:42:15 -0300, George Silva
<georger.silva at gmail.com> wrote:

> No this is not a localization problem. I just tested this.
> 
> Raster calculator makes expressions with ',' invalid. At least, on my
> machine (Mint 14)
> 
> This is the output of my locales:

  Pretty much like mine, except that I don't have any "en_US.UTF-8".  ;)

> 
> LANG=en_US.UTF-8
> LANGUAGE=
> LC_CTYPE="en_US.UTF-8"
> LC_NUMERIC=pt_BR.UTF-8
> LC_TIME="en_US.UTF-8"
> LC_COLLATE="en_US.UTF-8"
> LC_MONETARY=pt_BR.UTF-8
> LC_MESSAGES="en_US.UTF-8"
> LC_PAPER=pt_BR.UTF-8
> LC_NAME=pt_BR.UTF-8
> LC_ADDRESS=pt_BR.UTF-8
> LC_TELEPHONE=pt_BR.UTF-8
> LC_MEASUREMENT=pt_BR.UTF-8
> LC_IDENTIFICATION=pt_BR.UTF-8
> LC_ALL=
> 
> I just retried this. Grabbed a raster with floating point values and
> added 1.1 - the result is just an add by 1, without the 0.1. Giovanni
> was right about this, something is truncating these values in Raster
> Calculator to integers, and my input was 3.1, and the output 4.1
> (added just 1, instead of 1.1) when it should be 4.2.

  I still think it can have some relation with locale, perhaps in
another sense.  I don't know if I will be able to explain myself here.

  I have noticed some inconsistency in qgis on this aspect.  I already
stumbled on at least one situation where the comma separator weren't
accepted and I tried to divide by the inverse.  It was with qgis 2.6 (I
am using 2.8.2 in [Xu|U]buntu), at the time I was trying to convert the
line length from meters to kilometres multiplying by 0.001, IIRC
everything turned into zero.  After that, just in case, I tried to
divide by 1000 and I got the amount of meters I expected.

  There seems to exist some dark place between the keyboard (Qt?) and
the code where the localization seems to be mixed up and completely
screwed up.

  If I can suggest a test to Giacomo and George, in your Linux
installation open a terminal emulator (don't matter which one) and try
to execute qgis the following way:

  LC_ALL=C  qgis

This should "remove" the localization support and work with dot as the
decimal separator.   If it still gets the wrong result with the
expression  "band at map" * 0.1, I think that the problem can be
intrinsic to the code.   If it works correctly I think the problem is
somewhat related to the interface with Qt.

  I don't normally work with raster layers, but if you have a (very)
small example with floating point attribute I can try it here.

  Best regards.

> 
> George
> 
> On Fri, May 29, 2015 at 4:27 PM, Fernando M. Roxo da Motta
> <petro at roxo.org> wrote:
> 
> > On Fri, 29 May 2015 10:20:05 +0200, Giacomo Fontanelli
> > <giacomofontanelli76 at gmail.com> wrote:
> >
> >
> > > I used to work with qgis 2.8.1 in Lubuntu and in windows7.
> > >
> > > Each time I try to multiplicate a map for a number comprise
> > > between 0 and 1 (i.e. 0.1) I get a good results on windows OS,
> > > but I get a map with only 0 and NaN on Linux.
> > >
> > > Further, I get a correct result on Lubuntu if I divide by 10
> > > instead of multiplicate by 0.1.
> >
> >   It looks very much like a localization problem.  I guess that with
> > this name you are using a platform with Italian language.   I think
> > that the standard there is the same I have in Brazil, that is the
> > decimal separator is comma (,) instead of dot (.).   Try to use:
> >
> >
> >    "band at map" * 0,1
> >
> >
> >   Hope this helps.
> >
> >
> > >
> > > Conclusion
> > >
> > > "band at map" * 0.1 on windows = OK "band at map" * 0.1 on lubuntu =
> > > only 0 and NaN "band at map" / 10 on lubuntu = ok.
> > >
> > > I use the same gdal version and I always get a correct Float32
> > > map.
> > >
> > > Canyou help me?
> > >
> > > Thanx
> >
> >
> >
> >
> >
> >
> >
> >
> >   Roxo
> >
> > --
> > ---------------- Non luctari, ludare -------------------+ WYSIWYG
> > Fernando M. Roxo da Motta <petro at roxo.org>              | Editor?
> > Except where explicitly stated I speak on my own behalf.|  VI !!
> >       ( Usuário Linux registrado #39505 )               | I see
> > text, ------------ Quis custodiet ipsos custodes?-------------+ I
> > get text!
> >
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> >
> 
> 
> 

  Roxo

-- 
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <petro at roxo.org>              | Editor?
Except where explicitly stated I speak on my own behalf.|  VI !!
      ( Usuário Linux registrado #39505 )               | I see text,
------------ Quis custodiet ipsos custodes?-------------+ I get text!