To do this, I think you'll have to compare the extent (using the
extent() function) and/or number of rows and columns and/or resolution
of the two rasters. (Print the source code of compareRasters() and dig
through it to see what's being compared ...)
On 8/18/24 14:00, SIBYLLE STÖCKLI via R-help 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 <ikry...@disroot.org>
Sent: Friday, August 16, 2024 11:45 AM
To: sibylle.stoec...@gmx.ch
Cc: 'SIBYLLE STÖCKLI via R-help' <r-help@r-project.org>
Subject: Re: [R] allequal diff
В Fri, 16 Aug 2024 11:32:58 +0200
<sibylle.stoec...@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
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