Hi,
I just stumbled upon this while running a large model, and noticed that I couldn't easily find an answer:
IIUC r.mapcalc does not support scientific notation of floating point numbers (i.e. 2.540000e-05 instead of 0.0000254). Is that correct ?
How difficult would it be to implement the support of such notation ?
Moritz
On Thu, Jan 19, 2017 at 12:10 PM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:
Hi,
I just stumbled upon this while running a large model, and noticed that I
couldn't easily find an answer:IIUC r.mapcalc does not support scientific notation of floating point
numbers (i.e. 2.540000e-05 instead of 0.0000254). Is that correct ?How difficult would it be to implement the support of such notation ?
We just stumbled over the same issue... would be nice to have.
Markus
Moritz
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--
Markus Neteler, PhD
http://www.mundialis.de - free data with free software
http://grass.osgeo.org
http://courses.neteler.org/blog
Markus Neteler wrote:
> I just stumbled upon this while running a large model, and noticed that I
> couldn't easily find an answer:
>
> IIUC r.mapcalc does not support scientific notation of floating point
> numbers (i.e. 2.540000e-05 instead of 0.0000254). Is that correct ?
>
> How difficult would it be to implement the support of such notation ?We just stumbled over the same issue... would be nice to have.
It works here:
$ r.mapcalc "foo = 2.540000e-05"
$ r.info -r foo
min=2.54e-05
max=2.54e-05
$ g.version -gr
version=7.3.svn
date=2016
revision=r70088
build_date=2017-06-16
build_platform=x86_64-pc-linux-gnu
build_off_t_size=8
libgis_revision=70829
libgis_date="2017-04-04 08:43:02 +0100 (Tue, 04 Apr 2017) "
mapcalc.l specifically recognises exponential notation:
I [0-9]+
E [eE][-+]?[0-9]+
%%
{I}"."{I}?{E}? |
"."{I}{E}? {
yylval.fval = atof(yytext);
return DOUBLE;
}
atof() is specified as:
7.20.1.1 The atof function
...
[#2] The atof function converts the initial portion of the
string pointed to by nptr to double representation. Except
for the behavior on error, it is equivalent to
strtod(nptr, (char **)NULL)
and strtod() as
7.20.1.3 The strtod, strtof, and strtold functions
...
[#3] The expected form of the subject sequence is an
optional plus or minus sign, then one of the following:
-- a nonempty sequence of decimal digits optionally
containing a decimal-point character, then an optional
exponent part as defined in 6.4.4.2;
I note that any locale-specific varations are supposed to be in
addition to the format used by the "C" locale, so even if LC_NUMERIC
gets set (and it shouldn't), that shouldn't affect it.
Is this issue a wxGUI thing?
--
Glynn Clements <glynn@gclements.plus.com>
Hi Glynn !
On 16/06/17 02:35, Glynn Clements wrote:
Markus Neteler wrote:
I just stumbled upon this while running a large model, and noticed that I
couldn't easily find an answer:IIUC r.mapcalc does not support scientific notation of floating point
numbers (i.e. 2.540000e-05 instead of 0.0000254). Is that correct ?How difficult would it be to implement the support of such notation ?
We just stumbled over the same issue... would be nice to have.
It works here:
$ r.mapcalc "foo = 2.540000e-05"
$ r.info -r foo
min=2.54e-05
max=2.54e-05
I can confirm that this works here as well. I have to admit that I don't remember the details, but it was in the context of a python script, so maybe it was something in the script. And I can't remember what solution I found at the time.
It also works in python:
import grass.script as g
a = 2.54e-11
mce = "test = %e" % a
g.run_command('r.mapcalc', expre=mce, overwrite=True)
g.parse_command('r.info', flags='r', map_='test')
{u'max': u'2.54e-11', u'min': u'2.54e-11'}
Markus, what was your recent issue ? Maybe that will ring a bell for me...
[...]
Is this issue a wxGUI thing?
I wasn't confronted with it using the GUI, but running a script, AFAIR.
Moritz
On Jun 16, 2017 5:41 PM, “Moritz Lennert” <mlennert@club.worldonline.be> wrote:
…
Markus, what was your recent issue ? Maybe that will ring a bell for me…
I think we were on a system with Italian locale. I will ask if it was happening when using the GUI (likely yes).
Markus
On Fri, Jun 16, 2017 at 5:56 PM, Markus Neteler <neteler@osgeo.org> wrote:
On Jun 16, 2017 5:41 PM, “Moritz Lennert” <mlennert@club.worldonline.be> wrote:
…
Markus, what was your recent issue ? Maybe that will ring a bell for me…
I think we were on a system with Italian locale. I will ask if it was happening when using the GUI (likely yes).
this works:
r.mapcalc “foo = 2.0e-05”
r.mapcalc “foo = 2.e-05”
this does not work:
r.mapcalc “foo = 2e-05”
i.e. the number before ‘e’ must be a floating point number, otherwise the parser looks for the raster ‘2e’.
I guess this makes sense, maybe this needs mentioning in the manual.
Markus M
Markus
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