Re: [R-sig-Geo] help: Problem getting centroids inside lists
I understand, but I said "it doesn't work" because it gave an undesired
solution, but I'll try to be more explicit next time.
And I forgot to say that: s <- 1: length(ct)
And thank you for your advice, but the answer of Vijay Lulla resolved my
problem.
Regards,
Ariel
2018-09-12 17:43 GMT-03:00 MacQueen, Don :
> On any R mailing list, whenever you say "it doesn't work", you should
> always copy exactly what R command you gave, and any error messages.
>
> First notice:
>
> > ct$a$two
> SpatialPoints:
> lon lat
> [1,] -18 -2
> [2,] -16 50
> Coordinate Reference System (CRS) arguments: NA
>
> Then compare these:
>
> > coordinates(ct$a$two)
> lon lat
> [1,] -18 -2
> [2,] -16 50
>
> > coordinates(slot(ct$a$two,'coords'))
> lon lat
> [1,] -18 -2
> [2,] -16 50
>
> The results are the same. Why are you using the slot() function? There is
> no need, and it makes it more difficult to understand.
>
>
> You have assumed the mean() function will give you what you want when
> there are two points. It doesn't. Try it and see:
>
> > mean( coordinates(ct$a$two))
> [1] 3.5
>
> > mean(coordinates(slot(ct$a$two,'coords')))
> [1] 3.5
>
> Replace the mean() function with a function that will give you the
> "centroid" of two points, however you want to define that centroid. Perhaps
> the means of the two columns? R has a function for that.
>
> -
> In this bit:
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
> FUN = function(y)
>
> Using X = s is wrong because you haven't defined or created s anywhere. X
> should be ct.
>
> Also, X = ct[[x]] is wrong. When the first FUN is executed, it will be
> supplied automatically with the whole of ct$a, then ct$b. Try
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = x,
> FUN = function(y)
>
> The whole thing is easier to understand and test if you define the
> functions outside the lapply and sapply calls.
>
> -Don
> --
> Don MacQueen
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
> Lab cell 925-724-7509
>
>
>
> On 9/12/18, 11:42 AM, "R-sig-Geo on behalf of Ariel Fuentesdi" <
> r-sig-geo-boun...@r-project.org on behalf of ariel.fuente...@usach.cl>
> wrote:
>
> I went to a more general approach, that is:
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
> FUN = function(y) if(length(y)>1) geosphere::centroid(slot(y,
> "coords"))
> else sp::coordinates(slot(y, "coords"
>
> But now I want to add the case when they are only two elements. The
> dataset
> will be:
>
> ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat =
> c(-20,
> 5, 0)),
> two = data.frame(lon = c(-18, -16), lat = c(-2,
> 50))),
>b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1,
> 25,
> 5)),
> two = data.frame(lon = c(-90), lat = c(-1
> coordinates(ct$a$one) <- ~lon+lat
> coordinates(ct$a$two) <- ~lon+lat
> coordinates(ct$b$one) <- ~lon+lat
> coordinates(ct$b$two) <- ~lon+lat
>
> And I did the following but it doesn't work:
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
> FUN = function(y)
> if(length(y)>2) geosphere::centroid(slot(y, "coords"))
> else if (length(y) ==
> 1)
> sp::coordinates(slot(y, "coords"))
> else
> mean(sp::coordinates(slot(y, "coords")
>
> I need the result of each element of the list will be a matrix of two
> rows
> per column (named: one, two). How do I fix it?
>
> Regards,
> Ariel
>
> 2018-09-10 17:29 GMT-03:00 MacQueen, Don :
>
> > If all of your data frames had enough points then this should work:
> >
> > myfun1 <- function(le) {
> > list(one=geosphere::centroid(coordinates(le$one)),
> >two=geosphere::centroid(coordinates(le$two))
> >)
> > }
> >
> > lapply(ct, myfun1)
> >
> > To handle the one point case, try the following, which I think works
> with
> > your example data, but is untested if there just two points.
> > It also assumes the data frames are named 'one' and 'two', and will
> ignore
> > any others. To handle other names, I think you
> > could replace $one with [[1]] and $two with [[2]] .
> >
> > myfun <- function(le) {
> > list(one=if (length(le$one)>1) geosphere::centroid(
> coordinates(le$one))
> > else coodinates(le$one),
> >two=if (length(le$two)>1) geosphere::centroid(
> coordinates(le$two))
> > else coordinates(le$two)
> >)
> > }
> >
> > lapply(ct, myfun)
> >
> >
> > To see a little bit of what's going on, try
>
Re: [R-sig-Geo] help: Problem getting centroids inside lists
Maybe the following function is what you're looking for?
getcentroids <- function(x1) {
getcentroid <- function(x) {
coords <- slot(x, "coords")
numrows <- dim(coords)[1]
ret <- if(numrows == 2) {
matrix(apply(coords,2,mean), nrow=1)
} else {
if(numrows == 1) {
coords
} else {
geosphere::centroid(coords)
}
}
ret
}
r <- lapply(x1, function(x) as.data.frame(getcentroid(x)))
ret <- matrix(unlist(r), ncol=2, byrow=TRUE)
rownames(ret) <- names(r); colnames(ret) <- c("lon", "lat")
ret
}
Now call it as lapply(ct, getcentroids)
HTH,
Vijay.
On Wed, Sep 12, 2018 at 2:42 PM Ariel Fuentesdi
wrote:
> I went to a more general approach, that is:
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
> FUN = function(y) if(length(y)>1) geosphere::centroid(slot(y,
> "coords"))
> else sp::coordinates(slot(y, "coords"
>
> But now I want to add the case when they are only two elements. The dataset
> will be:
>
> ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat = c(-20,
> 5, 0)),
> two = data.frame(lon = c(-18, -16), lat = c(-2, 50))),
>b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1, 25,
> 5)),
> two = data.frame(lon = c(-90), lat = c(-1
> coordinates(ct$a$one) <- ~lon+lat
> coordinates(ct$a$two) <- ~lon+lat
> coordinates(ct$b$one) <- ~lon+lat
> coordinates(ct$b$two) <- ~lon+lat
>
> And I did the following but it doesn't work:
>
> ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
> FUN = function(y)
> if(length(y)>2) geosphere::centroid(slot(y, "coords"))
> else if (length(y) == 1)
> sp::coordinates(slot(y, "coords"))
> else
> mean(sp::coordinates(slot(y, "coords")
>
> I need the result of each element of the list will be a matrix of two rows
> per column (named: one, two). How do I fix it?
>
> Regards,
> Ariel
>
> 2018-09-10 17:29 GMT-03:00 MacQueen, Don :
>
> > If all of your data frames had enough points then this should work:
> >
> > myfun1 <- function(le) {
> > list(one=geosphere::centroid(coordinates(le$one)),
> >two=geosphere::centroid(coordinates(le$two))
> >)
> > }
> >
> > lapply(ct, myfun1)
> >
> > To handle the one point case, try the following, which I think works with
> > your example data, but is untested if there just two points.
> > It also assumes the data frames are named 'one' and 'two', and will
> ignore
> > any others. To handle other names, I think you
> > could replace $one with [[1]] and $two with [[2]] .
> >
> > myfun <- function(le) {
> > list(one=if (length(le$one)>1) geosphere::centroid(coordinates(le$one))
> > else coodinates(le$one),
> >two=if (length(le$two)>1) geosphere::centroid(coordinates(le$two))
> > else coordinates(le$two)
> >)
> > }
> >
> > lapply(ct, myfun)
> >
> >
> > To see a little bit of what's going on, try
> >
> > myfun(ct[[1]])
> > myfun1(ct[[1]])
> > myfun1(ct[[2]])
> > myfun(ct[[2]])
> >
> >
> >
> > I would also verify that the length method for objects of class
> > SpatialPoints does return the number of points, as it appears to:
> >
> > > class(ct$a$two)
> > [1] "SpatialPoints"
> > attr(,"package")
> > [1] "sp"
> >
> > > length(ct$a$one)
> > [1] 3
> > > length(ct$a$two)
> > [1] 3
> > > length(ct$a$two)
> > [1] 3
> > > length(ct$b$two)
> > [1] 1
> >
> > --
> > Don MacQueen
> > Lawrence Livermore National Laboratory
> > 7000 East Ave., L-627
> > Livermore, CA 94550
> > 925-423-1062
> > Lab cell 925-724-7509
> >
> >
> >
> > On 9/10/18, 10:56 AM, "R-sig-Geo on behalf of Ariel Fuentesdi" <
> > r-sig-geo-boun...@r-project.org on behalf of ariel.fuente...@usach.cl>
> > wrote:
> >
> > Hi everyone,
> >
> > I have a list of coordinates called "ct" and I want to extract the
> > centroids of each sublist, but it only works when it has only 3 or
> more
> > points. In ct$b$two only has one point; in that case, I would rescue
> > that
> > point as If it were a centroid.
> >
> > This is what I did:
> >
> > library(dplyr)
> > library(geosphere)
> >
> > ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat =
> > c(-20,
> > 5, 0)),
> > two = data.frame(lon = c(-18, -16, -6), lat =
> > c(-2, 50,
> > 10))),
> >b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1,
> > 25,
> > 5)),
> > two = data.frame(lon = c(-90), lat = c(-1
> >
> > coordinates(ct$a$one) <- ~lon+lat
> > coordinates(ct$a$two) <- ~lon+lat
> > coordinates(ct$b$one) <- ~lon+lat
> > coordinates(ct$b$two) <- ~lon+lat
> >
> > s <- 1:length(ct)
> > ctply <- list()
> > for (i in s){
> > for (j in 1:length(ct[[i]])) {
> > ctply[[i]][j] <- ifelse(test =
Re: [R-sig-Geo] help: Problem getting centroids inside lists
I went to a more general approach, that is:
ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
FUN = function(y) if(length(y)>1) geosphere::centroid(slot(y,
"coords"))
else sp::coordinates(slot(y, "coords"
But now I want to add the case when they are only two elements. The dataset
will be:
ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat = c(-20,
5, 0)),
two = data.frame(lon = c(-18, -16), lat = c(-2, 50))),
b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1, 25,
5)),
two = data.frame(lon = c(-90), lat = c(-1
coordinates(ct$a$one) <- ~lon+lat
coordinates(ct$a$two) <- ~lon+lat
coordinates(ct$b$one) <- ~lon+lat
coordinates(ct$b$two) <- ~lon+lat
And I did the following but it doesn't work:
ctply <- lapply(X = s, FUN = function(x) sapply(X = ct[[x]],
FUN = function(y)
if(length(y)>2) geosphere::centroid(slot(y, "coords"))
else if (length(y) == 1)
sp::coordinates(slot(y, "coords"))
else
mean(sp::coordinates(slot(y, "coords")
I need the result of each element of the list will be a matrix of two rows
per column (named: one, two). How do I fix it?
Regards,
Ariel
2018-09-10 17:29 GMT-03:00 MacQueen, Don :
> If all of your data frames had enough points then this should work:
>
> myfun1 <- function(le) {
> list(one=geosphere::centroid(coordinates(le$one)),
>two=geosphere::centroid(coordinates(le$two))
>)
> }
>
> lapply(ct, myfun1)
>
> To handle the one point case, try the following, which I think works with
> your example data, but is untested if there just two points.
> It also assumes the data frames are named 'one' and 'two', and will ignore
> any others. To handle other names, I think you
> could replace $one with [[1]] and $two with [[2]] .
>
> myfun <- function(le) {
> list(one=if (length(le$one)>1) geosphere::centroid(coordinates(le$one))
> else coodinates(le$one),
>two=if (length(le$two)>1) geosphere::centroid(coordinates(le$two))
> else coordinates(le$two)
>)
> }
>
> lapply(ct, myfun)
>
>
> To see a little bit of what's going on, try
>
> myfun(ct[[1]])
> myfun1(ct[[1]])
> myfun1(ct[[2]])
> myfun(ct[[2]])
>
>
>
> I would also verify that the length method for objects of class
> SpatialPoints does return the number of points, as it appears to:
>
> > class(ct$a$two)
> [1] "SpatialPoints"
> attr(,"package")
> [1] "sp"
>
> > length(ct$a$one)
> [1] 3
> > length(ct$a$two)
> [1] 3
> > length(ct$a$two)
> [1] 3
> > length(ct$b$two)
> [1] 1
>
> --
> Don MacQueen
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
> Lab cell 925-724-7509
>
>
>
> On 9/10/18, 10:56 AM, "R-sig-Geo on behalf of Ariel Fuentesdi" <
> r-sig-geo-boun...@r-project.org on behalf of ariel.fuente...@usach.cl>
> wrote:
>
> Hi everyone,
>
> I have a list of coordinates called "ct" and I want to extract the
> centroids of each sublist, but it only works when it has only 3 or more
> points. In ct$b$two only has one point; in that case, I would rescue
> that
> point as If it were a centroid.
>
> This is what I did:
>
> library(dplyr)
> library(geosphere)
>
> ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat =
> c(-20,
> 5, 0)),
> two = data.frame(lon = c(-18, -16, -6), lat =
> c(-2, 50,
> 10))),
>b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1,
> 25,
> 5)),
> two = data.frame(lon = c(-90), lat = c(-1
>
> coordinates(ct$a$one) <- ~lon+lat
> coordinates(ct$a$two) <- ~lon+lat
> coordinates(ct$b$one) <- ~lon+lat
> coordinates(ct$b$two) <- ~lon+lat
>
> s <- 1:length(ct)
> ctply <- list()
> for (i in s){
> for (j in 1:length(ct[[i]])) {
> ctply[[i]][j] <- ifelse(test = lengths(ct[[i]][1]) > 2, yes =
> sapply(X =
> ct[[i]][j],
> FUN = function(y) geosphere::centroid(slot(y, "coords"))), no =
> ct[[i]][j] )
> }
> }
>
> Thanks in advance
>
> Regards,
> Ariel
>
> [[alternative HTML version deleted]]
>
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> R-sig-Geo mailing list
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> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>
>
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Re: [R-sig-Geo] help: Problem getting centroids inside lists
If all of your data frames had enough points then this should work:
myfun1 <- function(le) {
list(one=geosphere::centroid(coordinates(le$one)),
two=geosphere::centroid(coordinates(le$two))
)
}
lapply(ct, myfun1)
To handle the one point case, try the following, which I think works with your
example data, but is untested if there just two points.
It also assumes the data frames are named 'one' and 'two', and will ignore any
others. To handle other names, I think you
could replace $one with [[1]] and $two with [[2]] .
myfun <- function(le) {
list(one=if (length(le$one)>1) geosphere::centroid(coordinates(le$one)) else
coodinates(le$one),
two=if (length(le$two)>1) geosphere::centroid(coordinates(le$two)) else
coordinates(le$two)
)
}
lapply(ct, myfun)
To see a little bit of what's going on, try
myfun(ct[[1]])
myfun1(ct[[1]])
myfun1(ct[[2]])
myfun(ct[[2]])
I would also verify that the length method for objects of class SpatialPoints
does return the number of points, as it appears to:
> class(ct$a$two)
[1] "SpatialPoints"
attr(,"package")
[1] "sp"
> length(ct$a$one)
[1] 3
> length(ct$a$two)
[1] 3
> length(ct$a$two)
[1] 3
> length(ct$b$two)
[1] 1
--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
Lab cell 925-724-7509
On 9/10/18, 10:56 AM, "R-sig-Geo on behalf of Ariel Fuentesdi"
wrote:
Hi everyone,
I have a list of coordinates called "ct" and I want to extract the
centroids of each sublist, but it only works when it has only 3 or more
points. In ct$b$two only has one point; in that case, I would rescue that
point as If it were a centroid.
This is what I did:
library(dplyr)
library(geosphere)
ct <- list(a = list(one = data.frame(lon = c(-180, -160, -60), lat = c(-20,
5, 0)),
two = data.frame(lon = c(-18, -16, -6), lat = c(-2, 50,
10))),
b = list(one = data.frame(lon = c(-9, -8, -3), lat = c(-1, 25,
5)),
two = data.frame(lon = c(-90), lat = c(-1
coordinates(ct$a$one) <- ~lon+lat
coordinates(ct$a$two) <- ~lon+lat
coordinates(ct$b$one) <- ~lon+lat
coordinates(ct$b$two) <- ~lon+lat
s <- 1:length(ct)
ctply <- list()
for (i in s){
for (j in 1:length(ct[[i]])) {
ctply[[i]][j] <- ifelse(test = lengths(ct[[i]][1]) > 2, yes = sapply(X =
ct[[i]][j],
FUN = function(y) geosphere::centroid(slot(y, "coords"))), no =
ct[[i]][j] )
}
}
Thanks in advance
Regards,
Ariel
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