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 <mailto: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 <house...@gmail.com
    <mailto: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-requ...@lists.osgeo.org> wrote:

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            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>
            To: Enrico Fiore <enricofi...@libero.it>
            Cc: qgis-user <qgis-user@lists.osgeo.org>
            Subject: Re: [Qgis-user] Symbolizing a discrete or a
            boolean raster
            Message-ID:
<cak6pvbxurm_e7drp+8sp9ampuux0+cn3gvxlpnjohhno85o...@mail.gmail.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> 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>
            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');>>
            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>
            >> Data: 09/01/2017 6.30
            >> A: "qgis-user"<qgis-user@lists.osgeo.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/009t00000074000000/
            >> 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
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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 <tel:+49%20176%2028011050> (DE)
    E s...@henriod.info <mailto:s...@henriod.info>
    W http://www.stat.kg
    W3W: nightfall.into.bucket
    <https://map.what3words.com/nightfall.into.bucket>  //
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