Hi Richard

this is a nice workaround, that I will also probably use in the future!
Thanks a lot!

However, this becomes unhandy:

   - if the raster doesn't contain all values between 1 and 50 (let's say,
   there are only classes 2, 23, 56 and 49) => need to manually remove all the
   unnecessary values
   - if the raster contains a discrete amount of decimal values (2.3, 4.5
   and 12.8)
   - if I don't know in advance the number of classes (which happens quite
   often: I receive a dataset that I don't know much about and want to quickly
   display / style it to explore it)

All the answers in this thread actually justify (IMO) the feature request:
it is at the moment possible to style discrete rasters in QGIS but only
using workarounds that are not necessarily adapted in all cases and that
are completely untransparent for beginners.

All the best

Stéphane


Le mardi 10 janvier 2017, Richard McDonnell <richard.mcdonn...@opw.ie> a
écrit :

> Harrissou,
>
> Not sure if this is a solution, or if anyone has already given you this
> answer, but.... if you know a classified raster has *50* values, which
> you wish to style individually, you could try setting
> *: *
>
>    - *Colour Interpolation* to *Linear*
>    - *Mode *to* Equal Interval*
>    - *Classes *to* 51 *(one more than the Max)
>
> I have only just tested this on a raster with 4 values and its worked for
> me!
> Hope this helps!
> Regards,
>
> Richard.
>
> On 10/01/2017 09:49, DelazJ wrote:
>
> Hi Stéphane,
>
> 2017-01-10 4:02 GMT+01:00 Stéphane Henriod <s...@henriod.info
> <javascript:_e(%7B%7D,'cvml','s...@henriod.info');>>:
>
>> Hi Chris
>>
>> this is very nice! I indeed didn't know this trick and will certainly use
>> it again in the future!
>>
>> However... :-)
>>
>> I am currently teaching QGIS to beginners and this for sure is not an
>> appropriate method for them (especially in the case you have to generate
>> the symbology file through a script)!
>>
>> Since the user can style continuous rasters with some "button-clicking",
>> I believe the same option should be available for discrete rasters as well.
>>
>> I am thus wondering if anyone else than me sees it as a priority for
>> QGIS? If yes, how to motivate the developers to take it for the next
>> release and / or how much would such a development cost? (I unfortunately
>> don't have the competences to do it myself)
>>
>> There have been some work done in the raster properties dialog in the
> upcoming 3.0. I don't know if your concern was covered though.
> If you want, you can move the question to the developer's list
> <http://qgis.org/en/site/getinvolved/mailinglists.html#qgis-developers-list>
> and discuss whether/how this can be implemented (and its requirements).
>
> Regards,
> Harrissou
>
> Thanks again and cheers!
>>
>> Stéphane
>>
>>
>> Le mardi 10 janvier 2017, Chris House <
>> <javascript:_e(%7B%7D,'cvml','house...@gmail.com');>house...@gmail.com
>> <javascript:_e(%7B%7D,'cvml','house...@gmail.com');>> a écrit :
>>
>>> Hi Stéphane,
>>>
>>> I don't know if this is what you are looking for or not but I have a
>>> method of classifying rasters by color based on a set (standard) colors.  I
>>> created a spreadsheet that has several required columns, value, red, green,
>>> blue...and you can have an optional field for a display value.  So say
>>> value 1 is water you can use that last column to name that value so that in
>>> the QGIS layer tree and in legend it says Water instead of value 1.
>>>
>>> save the spreadsheet as a csv and change the extension to .txt instead
>>> of .csv.
>>>
>>> I then go into the symbology section of the raster choose singleband
>>> pseudocolor. Use the folder to browse to your text file and click add.
>>> There is a format for this text file.  It is below.  If you need me to
>>> email it I will do that in direct email.
>>>
>>> # QGIS Generated Color Map Export File
>>> INTERPOLATION:EXACT
>>> -9999,0,0,0,255,NoData
>>> 0,176,176,176,255,Non-Forested
>>> 15,234,255,191,255,10 <=  CC < 20
>>> 25,187,230,149,255,20 <=  CC < 30
>>> 35,140,201,109,255,30 <=  CC < 40
>>> 45,98,176,74,255,40 <=  CC < 50
>>> 55,59,153,43,255,50 <= CC < 60
>>> 65,0,128,0,255,60 <=  CC < 70
>>> 75,15,92,11,255,70 <=  CC < 80
>>> 85,17,61,12,255,80 <=  CC < 90
>>> 95,16,36,12,255,90 <=  CC <= 100
>>>
>>> In my example if I don't assign a value it gets ignored by QGIS.  If you
>>> are wondering how to assign unique colors to say 200 unique values...just
>>> script it.  I have done this and as long as you have the number of unique
>>> values you want and to make them unique in the script it works.
>>>
>>> I hope this helps.  I know it isn't a "button" but to be honest I like
>>> this better.  If you already knew this...well then maybe it will help
>>> someone out in the future.
>>>
>>> --Chris
>>>
>>> On Mon, Jan 9, 2017 at 3:00 PM, <qgis-user-request@lists.osgeo
>>> <javascript:_e(%7B%7D,'cvml','qgis-user-request@lists.osgeo');>.org>
>>> wrote:
>>>
>>>> Send Qgis-user mailing list submissions to
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>>>>
>>>> When replying, please edit your Subject line so it is more specific
>>>> than "Re: Contents of Qgis-user digest..."
>>>>
>>>>
>>>> Today's Topics:
>>>>
>>>>    1. Re: Symbolizing a discrete or a boolean raster (Stéphane Henriod)
>>>>
>>>>
>>>> ----------------------------------------------------------------------
>>>>
>>>> Message: 1
>>>> Date: Mon, 9 Jan 2017 23:07:36 +0600
>>>> From: Stéphane Henriod <s...@henriod.info
>>>> <javascript:_e(%7B%7D,'cvml','s...@henriod.info');>>
>>>> To: Enrico Fiore <enricofi...@libero.it
>>>> <javascript:_e(%7B%7D,'cvml','enricofi...@libero.it');>>
>>>> Cc: qgis-user <qgis-user@lists.osgeo.org
>>>> <javascript:_e(%7B%7D,'cvml','qgis-user@lists.osgeo.org');>>
>>>> Subject: Re: [Qgis-user] Symbolizing a discrete or a boolean raster
>>>> Message-ID:
>>>>         <cak6pvbxurm_e7drp+8sp9ampuux0+cn3gvxlpnjohhno85o...@mail.gm
>>>> ail.com>
>>>> Content-Type: text/plain; charset="utf-8"
>>>>
>>>> Hi
>>>>
>>>> thanks for following up!
>>>>
>>>> It actually does part of the job!
>>>>
>>>> Using *Color interpretation: Exact*, I can indeed input the exact
>>>> values I
>>>> want to display (1,5 and 10) and all other pixels are hidden.
>>>>
>>>> HOWEVER,
>>>>
>>>> this still feels like a workaround:
>>>>
>>>>    - In the case of a discrete raster with many (> 50) unique values, I
>>>> do
>>>>    not want to input all of them manually
>>>>    - In some cases, I do not know in advance all the unique values of my
>>>>    raster
>>>>    - If I click on *Classify*, QGIS will choose X values (based on the
>>>>    number of classes and the classification method (continuous or equal
>>>>    interval)), which no longer match the "exact" values of my raster. It
>>>>    doesn't really make sense to classify a discrete rendering
>>>>
>>>> So I would say, we still need a render type "discrete raster" which
>>>> offers
>>>> the function to "retrieve all unique values" (and automatically apply a
>>>> discrete color ramp)
>>>>
>>>> Attached a (fake) test dataset.
>>>>
>>>> Thanks and cheers
>>>>
>>>> Stéphane
>>>>
>>>>
>>>> Le lundi 9 janvier 2017, Enrico Fiore <enricofi...@libero.it
>>>> <javascript:_e(%7B%7D,'cvml','enricofi...@libero.it');>> a écrit :
>>>>
>>>> > Hi,
>>>> > Sorry I can't do test, but if you use exact in color interpolation
>>>> > parameter?
>>>> >
>>>> > Cheers
>>>> >
>>>> > Enrico
>>>>
>>>>
>>>> Le lundi 9 janvier 2017, Stéphane Henriod <s...@henriod.info
>>>> <javascript:_e(%7B%7D,'cvml','s...@henriod.info');>> a écrit :
>>>>
>>>> > Hi
>>>> >
>>>> > unfortunately this is doing quite something different!
>>>> >
>>>> > If I have a raster with 10 Landcover classes (1,2,3,4,5,6,7,8,9,10)
>>>> and I
>>>> > want to display only 1,5 and 10, using *Discrete *(1: red, 5: yellow,
>>>> 10:
>>>> > blue) the following will happen:
>>>> >
>>>> > All pixels between 1 and 4 will be red
>>>> > All pixels between 5 and 9 will be yellow
>>>> > All pixels with 10 will be blue
>>>> >
>>>> > In this sense, the pixels are indeed not interpolated, but this still
>>>> is
>>>> > not the behavior I am expecting when styling discrete rasters.
>>>> >
>>>> > A "style discrete raster" function should offer the following:
>>>> >
>>>> >    - Automatically recover all unique values from the raster
>>>> >    - Only display the pixels to which the user has explicitly
>>>> assigned a
>>>> >    color
>>>> >
>>>> > But thanks for your hint, this can be helpful in other cases!
>>>> >
>>>> > Cheers
>>>> >
>>>> > Stéphane
>>>> >
>>>> >
>>>> > Le lundi 9 janvier 2017, Enrico Fiore <enricofi...@libero.it
>>>> <javascript:_e(%7B%7D,'cvml','enricofi...@libero.it');>
>>>> > <javascript:_e(%7B%7D,'cvml','enricofi...@libero.it
>>>> <javascript:_e(%7B%7D,'cvml','enricofi...@libero.it');>');>> a écrit :
>>>> >
>>>> >> Hi,
>>>> >> I think that the solution is in the QGIS documentation, that you can
>>>> read
>>>> >> here: <http://docs.qgis.org/2.14/en/docs/user_manual/working_with_r>
>>>> http://docs.qgis.org/2.14/en/docs/user_manual/working_with_r
>>>> >> aster/raster_properties.html#band-rendering
>>>> >> you have to use *Singleband pseudocolor *and set color interpolation
>>>> to
>>>> >> Discrete.
>>>> >>
>>>> >> Enrico
>>>> >>
>>>> >>
>>>> >> ----Messaggio originale----
>>>> >> Da: "Stéphane Henriod" <s...@henriod.info
>>>> <javascript:_e(%7B%7D,'cvml','s...@henriod.info');>>
>>>> >> Data: 09/01/2017 6.30
>>>> >> A: "qgis-user"<qgis-u...@lists.os
>>>> <javascript:_e(%7B%7D,'cvml','qgis-u...@lists.os');>geo.org>
>>>> >> Ogg: [Qgis-user] Symbolizing a discrete or a boolean raster
>>>> >>
>>>> >> Dear all
>>>> >>
>>>> >> As much as I love QGIS and use it in my everyday life, there is one
>>>> >> feature that I find particularly annoying: the styling of discrete
>>>> rasters.
>>>> >>
>>>> >> Basically, if I have a raster layer consisting of discrete landcover
>>>> >> values (1: water, 2: forest, 3: built-up), it seems that there is no
>>>> easy
>>>> >> way to style it. QGIS will assume that the data is continuous and
>>>> basically
>>>> >> interpolate the color between each value, which leads to the
>>>> following
>>>> >> issues:
>>>> >>
>>>> >> Let's say I want to display only water and built-up (values 1 and 3),
>>>> >> water in blue and built-up in grey. QGIS will still display the
>>>> forests,
>>>> >> using a color somewhere "between" blue and grey. My only left option
>>>> is to
>>>> >> process the raster to actually replace all the 2 with NoData, which
>>>> is
>>>> >> highly unpractical...
>>>> >>
>>>> >> Same if I have a boolean raster (only 0 and 1 values). QGIS will by
>>>> >> default make a color ramp from 0 to 0.9999.
>>>> >>
>>>> >> Also, the whole rather feels like a work-around for a missing
>>>> feature.
>>>> >>
>>>> >> I dream of a feature similar to this one from ArcGIS:
>>>> >> <http://resources.arcgis.com/en/help/main/10.1/index>
>>>> http://resources.arcgis.com/en/help/main/10.1/index.
>>>> >> html#/representing_unique_categories_such_as_land_use/009t00
>>>> 000074000000/
>>>> >> where all unique values are styled independently and where I can
>>>> easily
>>>> >> skip the values I don't want to see on my map.
>>>> >>
>>>> >> I asked a question here:
>>>> >> <http://gis.stackexchange.com/questions/194116/qgis-style-a-d>
>>>> http://gis.stackexchange.com/questions/194116/qgis-style-a-d
>>>> >> iscrete-raster
>>>> >>
>>>> >> and opened a ticket here:
>>>> >> <http://hub.qgis.org/issues/14845>http://hub.qgis.org/issues/14845
>>>> >>
>>>> >> But none has gotten lots of attention yet... Am I the only one to be
>>>> >> annoyed by this? If no, please raise your hand and let's try to get
>>>> some
>>>> >> momentum and see how to push this feature forward!
>>>> >>
>>>> >> Thanks a lot in advance!
>>>> >>
>>>> >> Cheers
>>>> >>
>>>> >> Stéphane
>>>> >>
>>>> >>
>>>> >
>>>>
>>>> --
>>>> Stéphane Henriod
>>>> CIM-Expert for GIS and Green Economy Statistics
>>>>
>>>> Национальный статистический комитет Кыргызской Республики
>>>> Кыргыз Республикасынын Улуттук статистика комитети
>>>> National Statistical Committee of the Kyrgyz Republic
>>>>
>>>> 374 Фрунзе ул. / Frunze str.
>>>> 720033 Бишкек / Bishkek
>>>>
>>>> T   +996 778 46 99 02 (KG)
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>>>> W   http://www.stat.kg
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>>>
>>>
>>
>> --
>> Stéphane Henriod
>> CIM-Expert for GIS and Green Economy Statistics
>>
>> Национальный статистический комитет Кыргызской Республики
>> Кыргыз Республикасынын Улуттук статистика комитети
>> National Statistical Committee of the Kyrgyz Republic
>>
>> 374 Фрунзе ул. / Frunze str.
>> 720033 Бишкек / Bishkek
>>
>> T   +996 778 46 99 02 (KG)
>> T   +49 176 280 11 050 <+49%20176%2028011050> (DE)
>> E    s...@henriod.info <javascript:_e(%7B%7D,'cvml','s...@henriod.info');>
>> W   http://www.stat.kg
>> W3W: nightfall.into.bucket
>> <https://map.what3words.com/nightfall.into.bucket>  //
>> запас.союз.дружный
>> <https://map.what3words.com/%D0%B7%D0%B0%D0%BF%D0%B0%D1%81.%D1%81%D0%BE%D1%8E%D0%B7.%D0%B4%D1%80%D1%83%D0%B6%D0%BD%D1%8B%D0%B9>
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>
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> --
> *Richard McDonnell*
> *GIS Specialist PgD GIS AssocSCSI*
> *OPW FRM Data Management*
> *52 Stephens Green, Dublin 2.*
> TEL: 01 6476543
>
> <http://www.opw.ie/>
>


-- 
Stéphane Henriod
CIM-Expert for GIS and Green Economy Statistics

Национальный статистический комитет Кыргызской Республики
Кыргыз Республикасынын Улуттук статистика комитети
National Statistical Committee of the Kyrgyz Republic

374 Фрунзе ул. / Frunze str.
720033 Бишкек / Bishkek

T   +996 778 46 99 02 (KG)
T   +49 176 280 11 050 (DE)
E    s...@henriod.info
W   http://www.stat.kg
W3W: nightfall.into.bucket
<https://map.what3words.com/nightfall.into.bucket>  //  запас.союз.дружный
<https://map.what3words.com/запас.союз.дружный>
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