* Markus Metz <[email protected]> [2018-02-26 14:38:08 +0100]:

On Mon, Feb 26, 2018 at 1:31 PM, Nikos Alexandris <[email protected]>
wrote:

* Markus Metz <[email protected]> [2018-02-26 13:01:35 +0100]:

On Mon, Feb 26, 2018 at 11:19 AM, Gra <[email protected]> wrote:


Dear community

I use r.cross to combine and then reclassify a set of indicators.

I realised that r.cross doesn't work correctly.

I have two inputs maps with values from 1 to 3 each.


the problem is that r.category doesn't list the first combination (eg 1

to 1)


eg
r.category map=myinput@in_data


0
1 category 1; category 2
2 category 1; category 3
3 category 2; category 1
4 category 2; category 2
5 category 2; category 3
6 category 3; category 1
7 category 3; category 2
8 category 3; category 3

in reality the first combination exists (0 is empty but  I should have

there category 1; category 1)

the problem is that I have to iterate on 700 cases and I wont check and

correct manually.


could  you fix it?


Please try trunk r72281


Works for me, thank you.


What about the -z flag, though?

The manual reads:

With the -z flag zero data values are not crossed. This means that if a
zero category value occurs in any input data layer, the combination is
assigned to category zero in the resulting map layer, even if other data
layers contain non-zero data. In the example given above, use of the -z
option would cause 3 categories to be generated instead of 5.

The -z flag does not behave as explained in the manual. It comes from the
old days when there was no NULL encoding in GRASS, and zero was used as
nodata. Now the -z flag means that with the -z flag, NULL values are not
crossed, not that zero data are not crossed. This has been introduced in
2013 with r55276. The results of r.cross without the -z flag might look
strange if any of the input maps contains NULL cells.

Markus M

Maybe renaming to -n (in future versions) ?

Nikos

By the way, it should be: "In the following example..." and not "In the
example given above...".

Nikos


Markus M

thanks
Grazia

--
Nikos Alexandris | Remote Sensing & Geomatics
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