[GRASS-user] r.kappa query

[daniel mcinerney]

Thanks for your email Markus. That's a necessary fix
to r.kappa - one that may not be immediately
obvious if the errors of omission and commission are more
evenly dispersed between classes.

Regarding the individual class errors, would it make sense to
simplify or standardise the values: -999.0000; -nan and NA
that are each reported within the r.kappa output?

Regards,
Daniel.

On Fri, Apr 1, 2011 at 3:42 PM, Markus Metz <
markus.metz.giswork at googlemail.com> wrote:

> On Fri, Apr 1, 2011 at 2:45 PM, daniel mcinerney
> <daniel.o.mcinerney at gmail.com> wrote:
> > Hi list,
> >
> > I have a query regarding the error matrix produced
> > using r.kappa (in GRASS 6.4.0 RC6) and hoping that
> > the following will help someone to replicate my findings.
> > From what I see, the error matrix is mis-labeling the
> > rows/columns in the matrix.
> >
> Right, I noticed that some months ago, but fixed it only in grass 7.
> Now also fixed in 6.5 and 6.4 (r45818 and r45819, respectively).
>
> Markus M
>
> > Using the spearfish dataset, I digitised 18 points
> > to create a reference dataset to validate
> > the classification, in this case the raster 'landcover.orig'
> > For the purposes of the test and simplicity, I ensured
> > that the points  were located within two landcover classes
> > (raster values 42 and 81). The following steps were carried out
> > to generate the output from r.kappa
> >
> >
> > #Create reference dataset
> > d.where | r.what input=landcover.orig > kappa_test.txt
> >
> > For the purposes of this test, I deliberately changed the
> > landcover class from 42 to 32 in the validation dataset [1]
> > This will create an off-diagonal value in the error matrix.
> >
> > #Create the vector point from ascii and convert to raster
> > v.in.ascii input=kappa_test output=kapp_test cat=4
> > v.to.rast input=kapp_test output=validation use=cat
> >
> > #Run r.kappa
> > r.kappa classification=landcover.orig reference=validation
> > output=validation.txt
> >
> > The output from r.kappa  (validation.txt) is below, however, it appears
> > to me that the matrix is transposed, i.e. the horizontal values
> > (MAP1) should in fact be vertical. From my interpretation, the error
> > matrix indicates that 8 validation points with the value 42 were
> > classified as 32, but in fact it should state that 8 points with
> > the value of 32 were classified as 42? Can anyone confirm
> > my findings?
> >
> > Thanks in advance.
> >
> > Regards,
> > Daniel.
> >
> >
> >                         ACCURACY ASSESSMENT
> > LOCATION: spearfish60                           Fri Apr  1 12:45:42 2011
> > MASK: none
> > MAPS: MAP1 = Categories (validation in user1)
> >       MAP2 = (untitled) (landcover.orig in PERMANENT)
> >
> > Error Matrix
> > Panel #1 of 1
> >                           MAP1
> >      cat#       32      42      81      Row Sum
> >  M    32        0       8       0       8
> >  A    42        0       0       0       0
> >  P    81        0       0       10      10
> > Col Sum         0       8       10      18
> >
> >
> > Cats    % Commission    % Ommission     Estimated Kappa
> > 32      100.000000      -nan    -999.000000
> > 42      NA              NA              NA
> > 81      0.000000        0.000000        1.000000
> >
> > Kappa           Kappa Variance
> > 0.357143        0.002343
> >
> > Obs Correct     Total Obs       % Observed Correct
> > 10              18              55.555556
> >
> >
> >
> > [1]
> > #validation input
> > 590188.6875|4919453.8125||32
> > 590188.6875|4918947||32
> > 590307.9375|4918350.75||32
> > 590576.25|4917694.875||32
> > 590307.9375|4917694.875||32
> > 590546.4375|4919364.375||32
> > 590874.375|4919364.375||32
> > 590904.1875|4919483.625||32
> > 603604.3125|4922047.5||81
> > 603336|4922315.8125||81
> > 603514.875|4922464.875||81
> > 603604.3125|4922256.1875||81
> > 603634.125|4922107.125||81
> > 603693.75|4921987.875||81
> > 603962.0625|4921987.875||81
> > 603753.375|4921600.3125||81
> > 603962.0625|4922047.5||81
> > 598983.375|4922256.1875||81
> >
> >
> >
> >
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> >
>
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