[R] allequal diff

Mon Aug 19 14:35:01 CEST 2024

Dear Ben and Bert

Thanks very much for the interesting discussion

Yes that why I was additionally using compareRaster(r1,r2) and then resample (r2, r1) to adapt the extend.

library(raster)
r1 <- raster("")
r2 <- raster("f")
compareRaster(r1, r2)

extent(r1)
extent(r2)

r2_resampled <- resample(r2, r1)
compareRaster(r1, r2_resampled)

CompareRaster:
Evaluate whether a two or more Raster* objects have the same extent, number of rows and columns, projection, resolution, and origin (or a subset of these comparisons).

Kind regards
Sibylle

-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Bert Gunter
Sent: Sunday, August 18, 2024 11:21 PM
To: Ben Bolker <bbolker using gmail.com>
Cc: r-help using r-project.org
Subject: Re: [R] allequal diff

Ah...I see.

Perhaps, then, the maintainer should be contacted, as the desired functionality seems similar to that provided in other all.equal methods. I realize that this may often not elicit a (prompt) response.

-- Bert

On Sun, Aug 18, 2024 at 11:50 AM Ben Bolker <bbolker using gmail.com> wrote:
>
>     The OP's original problem is that the all.equal method for raster 
> objects (raster:::all.equal.raster), which is a wrapper around the
> compareRaster() function, compares a bunch of different properties of 
> rasters (extent, resolution, values, etc.) and only returns a single 
> overall logical (TRUE/FALSE) value. OP wanted to see the magnitude of 
> the difference (as you could get for more typical all.equal methods by 
> using tolerance=0), but in order to do that one has to dig into the 
> code of compareRaster() and pull out code to make the particular 
> comparisons one wants by applying all.equal to specific components of 
> the raster (it would be nice if there were a built-in way to get this 
> information, but I don't know of one)
>
> On 8/18/24 14:40, Bert Gunter wrote:
> > "Is it true that all.equal just compares y values?"
> >
> > The following may be a bit more than you may have wanted, but I hope 
> > it is nevertheless useful.
> >
> > The first place you should go to for questions like this is the Help 
> > system, not here, i.e.
> > ?all.equal
> >
> > When you do this, you will find that all.equal() is a so-called S3 
> > generic function, which, among other things, means that it works 
> > differently (i.e. "dispatches") depending on its (usually) first 
> > argument. So, for example, if the first argument is of (S3) class 
> > "numeric", it will call the default method, all.equal.default(); if 
> > it's a function, it will call all.equal.function().  Help for 
> > all.equal's basic methods is found in the single all.equal (base) 
> > Help page. However, for non-base R packages, there may be other 
> > different methods provided for classed objects, e.g. perhaps of class "raster"
> > that would be found by ?all.equal.raster . Or maybe not, if the 
> > class "inherits" from another class, such as "matrix" (Warning: I am 
> > completely unfamiliar with the raster package, so these specifics 
> > are very likely wrong).
> >
> > To sort this sort of thing out, It would probably be useful for you 
> > to find a tutorial on R's S3 class  system (which is really a form 
> > of multiple dispatch) and spend some time with it. There are many 
> > good ones out there. This S3 system is widely used within R and many 
> > packages, so doing this sort of homework now should serve you well 
> > in your future R journey.
> >
> > All IMO obviously.
> >
> > Cheers,
> > Bert
> >
> >
> > On Sun, Aug 18, 2024 at 11:00 AM SIBYLLE STÖCKLI via R-help 
> > <r-help using r-project.org> wrote:
> >> Dear Ivan
> >>
> >> Thanks a lot for this very nice example.
> >>
> >> Is it true that all.equal just compares y values?
> >> Based on this help here I think so and the value I got is the difference for the y-values.
> >> https://www.statology.org/all-equal-function-r/
> >>
> >> However, here I see x and y testing?
> >> https://www.rdocumentation.org/packages/base/versions/3.6.2/topics/
> >> all.equal I am actually interested in the x values (x-y 
> >> coordinates). Test if x-y coordinates of both 25-m-pixel rasters are the same. Ther may be a small shift or differences in the number of decimal places.
> >>
> >> Kind regards
> >> Sibylle
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Ivan Krylov <ikrylov using disroot.org>
> >> Sent: Friday, August 16, 2024 11:45 AM
> >> To: sibylle.stoeckli using gmx.ch
> >> Cc: 'SIBYLLE STÖCKLI via R-help' <r-help using r-project.org>
> >> Subject: Re: [R] allequal diff
> >>
> >> В Fri, 16 Aug 2024 11:32:58 +0200
> >> <sibylle.stoeckli using gmx.ch> пишет:
> >>
> >>> # values and mask r1
> >>> r1 <- getValues(r1)
> >>> mask1 <- is.na(r1)
> >>> # Do the same for r2
> >>> r2 <- getValues(r2_resampled)
> >>> mask2 <- is.na(r2)
> >>>
> >>> # Combine the masks
> >>> all.equal(r1[!(mask1 & mask2)], r2[!(mask1 & mask2)])
> >> Let's consider a more tangible example:
> >>
> >> # The vectors `x` and `y` start out equal x <- y <- 1:10 # But then 
> >> their different elements are made missing x[c(1,3,4)] <- NA 
> >> y[c(3,8)] <- NA
> >>
> >> Now, `is.na(x) & is.na(y)` gives the third element as the only element missing in both x and y:
> >>
> >> mask1 <- is.na(x)
> >> mask2 <- is.na(y)
> >> all.equal( # not the comparison you are looking for
> >>   x[!(mask1 & mask2)], # still two more elements missing
> >>   y[!(mask1 & mask2)]  # still one more element missing
> >> )
> >>
> >> If you want to ignore all missing elements, you should combine the masks using the element-wise "or" operation ("missing in x and/or y"), not the element-wise "and" operation ("missing in both x and y at the same time"):
> >>
> >> mask1 & mask2 # drops element 3
> >> # [1] FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> >> mask1 | mask2 # drops elements 1, 3, 4, 8 # [1]  TRUE FALSE  TRUE  
> >> TRUE FALSE FALSE FALSE  TRUE FALSE FALSE
> >>
> >> --
> >> Best regards,
> >> Ivan
> >>
> >> ______________________________________________
> >> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see 
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> >> PLEASE do read the posting guide 
> >> https://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see 
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide 
> > https://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see 
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

______________________________________________
R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.