[GRASS-user] help t.rast.algebra

[Veronica Andreo]

Thanks, Sören!

I anxiously await for that paper :)

Cheers,
Vero
El sep 25, 2015 12:31 PM, "Sören Gebbert" <soerengebbert at googlemail.com>
escribió:

> Hi,
> Sorry, i am unable to help here, since the algebra is a deep mistery for
> me as well. I think that after i have finished a paper about it, the
> algebra will be much better documented.
>
> Ciao
> Sören
> Am 25.09.2015 16:40 schrieb "Veronica Andreo" <veroandreo at gmail.com>:
>
>> Hi Moritz,
>>
>> I eventually solved it like this:
>>
>> t.rast.aggregate -s input=cla granularity="1 years" method=minimum
>> output=yearly_min basename=yearly_min
>> t.rast.aggregate -s input=cla granularity="1 months" method=minimum
>> output=monthly_min basename=monthly_min
>>
>> YEAR_I=2003 ; YEAR_F=2013
>> MONTH_I=1 ;MONTH_F=12
>>
>> for YEAR in `seq $YEAR_I $YEAR_F` ; do
>> for MONTH in `seq -w $MONTH_I $MONTH_F` ; do
>> r.mapcalc expression="month_min_${YEAR}_${MONTH} =
>> if(monthly_min_${YEAR}_${MONTH} == yearly_min_${YEAR}, ${MONTH}, null())"
>> --o
>> done
>> done
>>
>> r.series input=`g.list type=raster pattern=*_ag sep=,`
>> output=month_of_min_mode method=mode
>>
>> Alternatively,
>>
>> 1. t.rast.aggregate -s input=cla granularity="1 months" method=minimum
>> output=monthly_min basename=monthly_min
>>
>> 2. t.rast.aggregate -s input=monthly_min granularity="1 years"
>> method=min_rast output=yearly_min_index
>>
>> 3. r.series input=`g.list rast pat=yearly_min_ind* sep=,` method=mode
>>
>> 4. r.reclass with
>>
>> 0 = 1
>> 1 = 2
>> 2 = 3
>> 3 = 4
>> 4 = 5
>> 5 = 6
>> 6 = 7
>> 7 = 8
>> 8 = 9
>> 9 = 10
>> 10 = 11
>> 11 = 12
>>
>> Meanwhile, I still think t.rast.algebra should do the job in one
>> command... I just cannot
>> figure it out (yet) from the manual page:
>> https://grass.osgeo.org/grass71/manuals/t.rast.algebra.html
>>
>> I keep studying it, though
>>
>> Thanks a lot!
>> Vero
>>
>>
>> 2015-09-24 3:58 GMT-03:00 Moritz Lennert <mlennert at club.worldonline.be>:
>>
>>> On 18/09/15 17:38, Veronica Andreo wrote:
>>>
>>>> Hi Soeren, list
>>>>
>>>> I need some help with t.rast.algebra. Well, if it is that my problem is
>>>> really a t.rast.algebra problem...
>>>>
>>>> I have 2 strds with different granularities. A is an annual time series
>>>> that contains the min annual temperature, B is a monthly time series
>>>> containing the min monthly temperature. I want to compare the two of
>>>> them, and when a pixel of B equals that of A, I need to get the
>>>> start_month(B) but with the temporal resolution of A. So, what I want as
>>>> output is a yearly time series containing the month in which the minimum
>>>> temperature of each year occurs. Does that make any sense??
>>>>
>>>> I been studying t.rast.algebra all morning now and trying different kind
>>>> of relationships (with no success), and I got lost in the different
>>>> relationships and the different ways to express them.
>>>>
>>>> Can someone point me to the right way of using t.rast.algebra for this
>>>> problem?
>>>>
>>>
>>> No help for t.rast.algebra, but wouldn't looping over the years and
>>> applying t.rast.series with method=min_raster get you what you want ?
>>>
>>> Moritz
>>>
>>
>>
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