Thank you all for your solutions and comments. As Dr. Carlson mentioned, we leave rows 1 to 3 out as they are all zeroes. Then, the entries I need to select from m are ---------------- entry value ---------------- 4,1 ---> 1 5,2 ---> 2 6,3 ---> 3 7,1 ---> 1 8,2 ---> 2 9,3 ---> 3 10,4 ---> 4 11,5 ---> 5 12,1 ---> 1 Note that the entry [7,4] is zero, so we start from the first column in the 7th row and then select entry [7,1] instead. That's what I meant by "... the idea is to extract the diagonal elements until a zero is found." I should have said *entries* instead of _diagonal elements_. I am sorry Dr. Turner for the confusion. Starting with m R> m # [,1] [,2] [,3] [,4] [,5] # [1,] 0 0 0 0 0 # [2,] 0 0 0 0 0 # [3,] 0 0 0 0 0 # [4,] 1 2 3 0 0 # [5,] 1 2 3 0 0 # [6,] 1 2 3 0 0 # [7,] 1 2 3 0 0 # [8,] 1 2 3 0 0 # [9,] 1 2 3 4 0 #[10,] 1 2 3 4 0 #[11,] 1 2 3 4 5 #[12,] 1 2 3 4 5 the first submatrix to work with is # [4,] 1 2 3 0 0 # [5,] 1 2 3 0 0 # [6,] 1 2 3 0 0 from which the elements of interest are 1, 2, 3. Note that the 7th row of m is not included here because m[7, 5] = 0. Further, the second submatrix is # [7,] 1 2 3 0 0 # [8,] 1 2 3 0 0 # [9,] 1 2 3 4 0 #[10,] 1 2 3 4 0 #[11,] 1 2 3 4 5 and the corresponding elements are 1, 2, 3, 4, 5. And the last matrix is #[12,] 1 2 3 4 5 from which the position [12,1] is selected. So, the resulting entries from this process are 1, 2, 3, 1, 2, 3, 4, 5, 1. Thank you in advance for any additional insight you may provide. Regards, Jorge Velez.- On Tue, Oct 27, 2015 at 4:06 PM, David L Carlson <dcarlson at tamu.edu> wrote:> I don't see how you are getting the result you provide. > > > m > [,1] [,2] [,3] [,4] [,5] > [1,] 0 0 0 0 0 > [2,] 0 0 0 0 0 > [3,] 0 0 0 0 0 > [4,] 1 2 3 0 0 > [5,] 1 2 3 0 0 > [6,] 1 2 3 0 0 > [7,] 1 2 3 0 0 > [8,] 1 2 3 0 0 > [9,] 1 2 3 4 0 > [10,] 1 2 3 4 0 > [11,] 1 2 3 4 5 > [12,] 1 2 3 4 5 > > t(sapply(1:8, function(x) diag(m[x:12, ]))) > [,1] [,2] [,3] [,4] [,5] > [1,] 0 0 0 0 0 > [2,] 0 0 3 0 0 > [3,] 0 2 3 0 0 > [4,] 1 2 3 0 0 > [5,] 1 2 3 0 0 > [6,] 1 2 3 4 0 > [7,] 1 2 3 4 5 > [8,] 1 2 3 4 5 > > These are all of the diagonals from the 1st through 8th rows. The first 3 > begin with 0 so we leave them out, but then we have 4th: 1, 2, 3; 5th: 1, > 2, 3; 6th: 1, 2, 3, 4, etc so you must have some additional rule in mind to > get your answer. > > ------------------------------------- > David L Carlson > Department of Anthropology > Texas A&M University > College Station, TX 77840-4352 > > > > -----Original Message----- > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Jorge I > Velez > Sent: Tuesday, October 27, 2015 2:44 PM > To: jim holtman > Cc: R-help > Subject: Re: [R] Extract entries from matrix > > Dear Jim, > > Thank you very much for your quick reply. > > I am sorry for the confusion it may have caused, but I messed up the > indexes in my example. I would like, from the following matrix "m" > > ## input > m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, > 0L, 0L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, 0L, 0L, 3L, 3L, > 3L, 3L, 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, > 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 5L, 5L), .Dim = c(12L, > 5L)) > > to obtain > > 1 2 3 1 2 3 4 5 1 > > Sure using m[idx] will give the desired result. The problem is that idx is > not known and needs to be determined from "m". I would like to use > something like > > extractDiagonals(m) > ## [1] 1 2 3 1 2 3 4 5 1 > > I look forward to your reply. Thanks in advance. > > Best regards, > Jorge Velez.- > > > > On Tue, Oct 27, 2015 at 2:31 PM, jim holtman <jholtman at gmail.com> wrote: > > > If you want to use the numbers you gave a the index into the matrix, then > > you can create a matrix with the values and then index into 'm'. I don't > > see a '4' in the output example you gave using your index values: > > > > > m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, > > + 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L, 2L, > > + 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, > > + 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, > > + 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L, 4L, > > + 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, > > + 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, > > + 5L), .Dim = c(22L, 5L)) > > > # create index matrix > > > indx <- matrix(c(4, 1, > > + 5, 2, > > + 6, 3, > > + 7, 1, > > + 8, 2, > > + 9, 3, > > + 10, 1, > > + 11, 2, > > + 12, 3), ncol = 2, byrow = TRUE) > > > > > > > > > m > > [,1] [,2] [,3] [,4] [,5] > > [1,] 0 0 0 0 0 > > [2,] 0 0 0 0 0 > > [3,] 0 0 0 0 0 > > [4,] 1 2 3 0 0 > > [5,] 1 2 3 0 0 > > [6,] 1 2 3 0 0 > > [7,] 1 2 3 0 0 > > [8,] 1 2 3 0 0 > > [9,] 1 2 3 4 0 > > [10,] 1 2 3 4 0 > > [11,] 1 2 3 4 5 > > [12,] 1 2 3 4 5 > > [13,] 1 2 3 4 5 > > [14,] 1 2 3 4 5 > > [15,] 1 2 3 4 5 > > [16,] 1 2 3 4 5 > > [17,] 1 2 3 4 5 > > [18,] 1 2 3 4 5 > > [19,] 1 2 3 4 5 > > [20,] 1 2 3 4 5 > > [21,] 1 2 3 4 5 > > [22,] 1 2 3 4 5 > > > indx > > [,1] [,2] > > [1,] 4 1 > > [2,] 5 2 > > [3,] 6 3 > > [4,] 7 1 > > [5,] 8 2 > > [6,] 9 3 > > [7,] 10 1 > > [8,] 11 2 > > [9,] 12 3 > > > m[indx] > > [1] 1 2 3 1 2 3 1 2 3 > > > > > > Jim Holtman > > Data Munger Guru > > > > What is the problem that you are trying to solve? > > Tell me what you want to do, not how you want to do it. > > > > On Tue, Oct 27, 2015 at 2:43 PM, Jorge I Velez <jorgeivanvelez at gmail.com > > > > wrote: > > > >> Dear R-help, > >> > >> I am working with a matrix "m" from which I would like to extract some > >> elements. An toy example is as follows: > >> > >> ## input matrix > >> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, > >> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L, 2L, > >> 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, > >> 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, > >> 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L, 4L, > >> 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, > >> 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, > >> 5L), .Dim = c(22L, 5L)) > >> > >> R> m > >> # [,1] [,2] [,3] [,4] [,5] > >> # [1,] 0 0 0 0 0 > >> # [2,] 0 0 0 0 0 > >> # [3,] 0 0 0 0 0 > >> # [4,] 1 2 3 0 0 > >> # [5,] 1 2 3 0 0 > >> # [6,] 1 2 3 0 0 > >> # [7,] 1 2 3 0 0 > >> # [8,] 1 2 3 0 0 > >> # [9,] 1 2 3 4 0 > >> # [10,] 1 2 3 4 0 > >> # [11,] 1 2 3 4 5 > >> # [12,] 1 2 3 4 5 > >> > >> >From "m", I would like to extract the entries > >> > >> 4, 1 > >> 5, 2 > >> 6, 3 > >> 7, 1 > >> 8, 2 > >> 9, 3 > >> 10, 1 > >> 11, 2 > >> 12, 3 > >> > >> so at the end of applying a function "f" to "m" I get > >> > >> 1, 2, 3, 1, 2, 3, 4, 1, 2, 3 > >> > >> > >> Basically the idea is to extract the diagonal elements until a zero is > >> found. > >> > >> In the real problem the dimensions of "m" are much bigger, but this > >> smaller > >> version of "m" illustrate what needs to be done. > >> > >> I would greatly appreciate any ideas on how to do this. > >> > >> Thanks in advance, > >> Jorge Velez.- > >> > >> [[alternative HTML version deleted]] > >> > >> ______________________________________________ > >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > >> https://stat.ethz.ch/mailman/listinfo/r-help > >> PLEASE do read the posting guide > >> http://www.R-project.org/posting-guide.html > >> and provide commented, minimal, self-contained, reproducible code. > >> > > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
Dear all, I thought I would better send an image illustrating that the problem is (hope the file gets through). In the picture, the matrix "m" is given by ## input m <- structure(c(0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 3, 3, 3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5), .Dim = c(12L, 5L)) We start from the entry [1,1] and select all values in the diagonal until we find the first zero. That is, we select the values in purple. Because the first zero is found in [4,4], the next matrix begins in the 4th row. The values of interest would be 1, 2, 3, 4, 5 (light blue). The last value in this resulting vector is entry m[8,5], which is located at the maximum number of columns of m. Hence, the next matrix to work with starts at row 9 and the values of interest are 1, 2 (in orange). The output vector would then be of the same length as the number of rows in "m", and would contain the elements previously selected. Any ideas on how to proceed? Thank you very much in advance. Best regards, Jorge Velez.- On Tue, Oct 27, 2015 at 4:38 PM, Jorge I Velez <jorgeivanvelez at gmail.com> wrote:> Thank you all for your solutions and comments. > > As Dr. Carlson mentioned, we leave rows 1 to 3 out as they are all zeroes. > Then, the entries I need to select from m are > > ---------------- > entry value > ---------------- > 4,1 ---> 1 > 5,2 ---> 2 > 6,3 ---> 3 > 7,1 ---> 1 > 8,2 ---> 2 > 9,3 ---> 3 > 10,4 ---> 4 > 11,5 ---> 5 > 12,1 ---> 1 > > Note that the entry [7,4] is zero, so we start from the first column in > the 7th row and then select entry [7,1] instead. That's what I meant by "... > the idea is to extract the diagonal elements until a zero is found." I > should have said *entries* instead of _diagonal elements_. I am sorry Dr. > Turner for the confusion. > > Starting with m > > R> m > # [,1] [,2] [,3] [,4] [,5] > # [1,] 0 0 0 0 0 > # [2,] 0 0 0 0 0 > # [3,] 0 0 0 0 0 > # [4,] 1 2 3 0 0 > # [5,] 1 2 3 0 0 > # [6,] 1 2 3 0 0 > # [7,] 1 2 3 0 0 > # [8,] 1 2 3 0 0 > # [9,] 1 2 3 4 0 > #[10,] 1 2 3 4 0 > #[11,] 1 2 3 4 5 > #[12,] 1 2 3 4 5 > > the first submatrix to work with is > > # [4,] 1 2 3 0 0 > # [5,] 1 2 3 0 0 > # [6,] 1 2 3 0 0 > > from which the elements of interest are 1, 2, 3. Note that the 7th row of > m is not included here because m[7, 5] = 0. > > Further, the second submatrix is > > # [7,] 1 2 3 0 0 > # [8,] 1 2 3 0 0 > # [9,] 1 2 3 4 0 > #[10,] 1 2 3 4 0 > #[11,] 1 2 3 4 5 > > and the corresponding elements are 1, 2, 3, 4, 5. > > And the last matrix is > > #[12,] 1 2 3 4 5 > > from which the position [12,1] is selected. > > So, the resulting entries from this process are 1, 2, 3, 1, 2, 3, 4, 5, 1. > > Thank you in advance for any additional insight you may provide. > > Regards, > Jorge Velez.- > > > > On Tue, Oct 27, 2015 at 4:06 PM, David L Carlson <dcarlson at tamu.edu> > wrote: > >> I don't see how you are getting the result you provide. >> >> > m >> [,1] [,2] [,3] [,4] [,5] >> [1,] 0 0 0 0 0 >> [2,] 0 0 0 0 0 >> [3,] 0 0 0 0 0 >> [4,] 1 2 3 0 0 >> [5,] 1 2 3 0 0 >> [6,] 1 2 3 0 0 >> [7,] 1 2 3 0 0 >> [8,] 1 2 3 0 0 >> [9,] 1 2 3 4 0 >> [10,] 1 2 3 4 0 >> [11,] 1 2 3 4 5 >> [12,] 1 2 3 4 5 >> > t(sapply(1:8, function(x) diag(m[x:12, ]))) >> [,1] [,2] [,3] [,4] [,5] >> [1,] 0 0 0 0 0 >> [2,] 0 0 3 0 0 >> [3,] 0 2 3 0 0 >> [4,] 1 2 3 0 0 >> [5,] 1 2 3 0 0 >> [6,] 1 2 3 4 0 >> [7,] 1 2 3 4 5 >> [8,] 1 2 3 4 5 >> >> These are all of the diagonals from the 1st through 8th rows. The first 3 >> begin with 0 so we leave them out, but then we have 4th: 1, 2, 3; 5th: 1, >> 2, 3; 6th: 1, 2, 3, 4, etc so you must have some additional rule in mind to >> get your answer. >> >> ------------------------------------- >> David L Carlson >> Department of Anthropology >> Texas A&M University >> College Station, TX 77840-4352 >> >> >> >> -----Original Message----- >> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Jorge I >> Velez >> Sent: Tuesday, October 27, 2015 2:44 PM >> To: jim holtman >> Cc: R-help >> Subject: Re: [R] Extract entries from matrix >> >> Dear Jim, >> >> Thank you very much for your quick reply. >> >> I am sorry for the confusion it may have caused, but I messed up the >> indexes in my example. I would like, from the following matrix "m" >> >> ## input >> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, >> 0L, 0L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, 0L, 0L, 3L, 3L, >> 3L, 3L, 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, >> 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 5L, 5L), .Dim = c(12L, >> 5L)) >> >> to obtain >> >> 1 2 3 1 2 3 4 5 1 >> >> Sure using m[idx] will give the desired result. The problem is that idx >> is >> not known and needs to be determined from "m". I would like to use >> something like >> >> extractDiagonals(m) >> ## [1] 1 2 3 1 2 3 4 5 1 >> >> I look forward to your reply. Thanks in advance. >> >> Best regards, >> Jorge Velez.- >> >> >> >> On Tue, Oct 27, 2015 at 2:31 PM, jim holtman <jholtman at gmail.com> wrote: >> >> > If you want to use the numbers you gave a the index into the matrix, >> then >> > you can create a matrix with the values and then index into 'm'. I >> don't >> > see a '4' in the output example you gave using your index values: >> > >> > > m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, >> > + 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L, 2L, >> > + 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, >> > + 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, >> > + 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L, 4L, >> > + 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, >> > + 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, >> > + 5L), .Dim = c(22L, 5L)) >> > > # create index matrix >> > > indx <- matrix(c(4, 1, >> > + 5, 2, >> > + 6, 3, >> > + 7, 1, >> > + 8, 2, >> > + 9, 3, >> > + 10, 1, >> > + 11, 2, >> > + 12, 3), ncol = 2, byrow = TRUE) >> > > >> > > >> > > m >> > [,1] [,2] [,3] [,4] [,5] >> > [1,] 0 0 0 0 0 >> > [2,] 0 0 0 0 0 >> > [3,] 0 0 0 0 0 >> > [4,] 1 2 3 0 0 >> > [5,] 1 2 3 0 0 >> > [6,] 1 2 3 0 0 >> > [7,] 1 2 3 0 0 >> > [8,] 1 2 3 0 0 >> > [9,] 1 2 3 4 0 >> > [10,] 1 2 3 4 0 >> > [11,] 1 2 3 4 5 >> > [12,] 1 2 3 4 5 >> > [13,] 1 2 3 4 5 >> > [14,] 1 2 3 4 5 >> > [15,] 1 2 3 4 5 >> > [16,] 1 2 3 4 5 >> > [17,] 1 2 3 4 5 >> > [18,] 1 2 3 4 5 >> > [19,] 1 2 3 4 5 >> > [20,] 1 2 3 4 5 >> > [21,] 1 2 3 4 5 >> > [22,] 1 2 3 4 5 >> > > indx >> > [,1] [,2] >> > [1,] 4 1 >> > [2,] 5 2 >> > [3,] 6 3 >> > [4,] 7 1 >> > [5,] 8 2 >> > [6,] 9 3 >> > [7,] 10 1 >> > [8,] 11 2 >> > [9,] 12 3 >> > > m[indx] >> > [1] 1 2 3 1 2 3 1 2 3 >> > >> > >> > Jim Holtman >> > Data Munger Guru >> > >> > What is the problem that you are trying to solve? >> > Tell me what you want to do, not how you want to do it. >> > >> > On Tue, Oct 27, 2015 at 2:43 PM, Jorge I Velez < >> jorgeivanvelez at gmail.com> >> > wrote: >> > >> >> Dear R-help, >> >> >> >> I am working with a matrix "m" from which I would like to extract some >> >> elements. An toy example is as follows: >> >> >> >> ## input matrix >> >> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, >> >> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L, 2L, >> >> 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, >> >> 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, >> >> 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L, 4L, >> >> 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, >> >> 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, >> >> 5L), .Dim = c(22L, 5L)) >> >> >> >> R> m >> >> # [,1] [,2] [,3] [,4] [,5] >> >> # [1,] 0 0 0 0 0 >> >> # [2,] 0 0 0 0 0 >> >> # [3,] 0 0 0 0 0 >> >> # [4,] 1 2 3 0 0 >> >> # [5,] 1 2 3 0 0 >> >> # [6,] 1 2 3 0 0 >> >> # [7,] 1 2 3 0 0 >> >> # [8,] 1 2 3 0 0 >> >> # [9,] 1 2 3 4 0 >> >> # [10,] 1 2 3 4 0 >> >> # [11,] 1 2 3 4 5 >> >> # [12,] 1 2 3 4 5 >> >> >> >> >From "m", I would like to extract the entries >> >> >> >> 4, 1 >> >> 5, 2 >> >> 6, 3 >> >> 7, 1 >> >> 8, 2 >> >> 9, 3 >> >> 10, 1 >> >> 11, 2 >> >> 12, 3 >> >> >> >> so at the end of applying a function "f" to "m" I get >> >> >> >> 1, 2, 3, 1, 2, 3, 4, 1, 2, 3 >> >> >> >> >> >> Basically the idea is to extract the diagonal elements until a zero is >> >> found. >> >> >> >> In the real problem the dimensions of "m" are much bigger, but this >> >> smaller >> >> version of "m" illustrate what needs to be done. >> >> >> >> I would greatly appreciate any ideas on how to do this. >> >> >> >> Thanks in advance, >> >> Jorge Velez.- >> >> >> >> [[alternative HTML version deleted]] >> >> >> >> ______________________________________________ >> >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> >> https://stat.ethz.ch/mailman/listinfo/r-help >> >> PLEASE do read the posting guide >> >> http://www.R-project.org/posting-guide.html >> >> and provide commented, minimal, self-contained, reproducible code. >> >> >> > >> > >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > >-------------- next part -------------- A non-text attachment was scrubbed... Name: example.png Type: image/png Size: 35497 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20151028/4d4d0860/attachment.png>
Your code does not produce the matrix in your image.
The first three rows contain all-zeros and the last row is missing.
The following line fixes that:
m <- rbind(m[-(1:3), ], 1:5)
Given that matrix, the following code produces the output
you have illustrated. It's so trivial however that I suspect
something must be missing in your problem description.
v <- numeric(nrow(m))
j <- 1
for (i in 1:nrow(m)) {
if (j > ncol(m) || m[i,j] == 0) {
j <- 1
}
v[i] <- m[i,j]
j <- j+1
}
v
Note that this puts 0 in the output if
there is a zero in your first column and
the "diagonal". Your example didn't have that.
B.
On Oct 28, 2015, at 1:17 PM, Jorge I Velez <jorgeivanvelez at gmail.com>
wrote:
> Dear all,
>
> I thought I would better send an image illustrating that the problem is
> (hope the file gets through). In the picture, the matrix "m" is
given by
>
> ## input
> m <- structure(c(0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 2, 2,
> 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 3, 3, 3, 3, 3, 3, 3, 3, 3, 0, 0,
> 0, 0, 0, 0, 0, 0, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5,
> 5), .Dim = c(12L, 5L))
>
> We start from the entry [1,1] and select all values in the diagonal until
> we find the first zero. That is, we select the values in purple. Because
> the first zero is found in [4,4], the next matrix begins in the 4th row.
> The values of interest would be 1, 2, 3, 4, 5 (light blue). The last value
> in this resulting vector is entry m[8,5], which is located at the maximum
> number of columns of m. Hence, the next matrix to work with starts at row 9
> and the values of interest are 1, 2 (in orange).
>
> The output vector would then be of the same length as the number of rows in
> "m", and would contain the elements previously selected.
>
> Any ideas on how to proceed?
>
> Thank you very much in advance.
>
> Best regards,
> Jorge Velez.-
>
>
>
> On Tue, Oct 27, 2015 at 4:38 PM, Jorge I Velez <jorgeivanvelez at
gmail.com>
> wrote:
>
>> Thank you all for your solutions and comments.
>>
>> As Dr. Carlson mentioned, we leave rows 1 to 3 out as they are all
zeroes.
>> Then, the entries I need to select from m are
>>
>> ----------------
>> entry value
>> ----------------
>> 4,1 ---> 1
>> 5,2 ---> 2
>> 6,3 ---> 3
>> 7,1 ---> 1
>> 8,2 ---> 2
>> 9,3 ---> 3
>> 10,4 ---> 4
>> 11,5 ---> 5
>> 12,1 ---> 1
>>
>> Note that the entry [7,4] is zero, so we start from the first column in
>> the 7th row and then select entry [7,1] instead. That's what I
meant by "...
>> the idea is to extract the diagonal elements until a zero is
found." I
>> should have said *entries* instead of _diagonal elements_. I am sorry
Dr.
>> Turner for the confusion.
>>
>> Starting with m
>>
>> R> m
>> # [,1] [,2] [,3] [,4] [,5]
>> # [1,] 0 0 0 0 0
>> # [2,] 0 0 0 0 0
>> # [3,] 0 0 0 0 0
>> # [4,] 1 2 3 0 0
>> # [5,] 1 2 3 0 0
>> # [6,] 1 2 3 0 0
>> # [7,] 1 2 3 0 0
>> # [8,] 1 2 3 0 0
>> # [9,] 1 2 3 4 0
>> #[10,] 1 2 3 4 0
>> #[11,] 1 2 3 4 5
>> #[12,] 1 2 3 4 5
>>
>> the first submatrix to work with is
>>
>> # [4,] 1 2 3 0 0
>> # [5,] 1 2 3 0 0
>> # [6,] 1 2 3 0 0
>>
>> from which the elements of interest are 1, 2, 3. Note that the 7th row
of
>> m is not included here because m[7, 5] = 0.
>>
>> Further, the second submatrix is
>>
>> # [7,] 1 2 3 0 0
>> # [8,] 1 2 3 0 0
>> # [9,] 1 2 3 4 0
>> #[10,] 1 2 3 4 0
>> #[11,] 1 2 3 4 5
>>
>> and the corresponding elements are 1, 2, 3, 4, 5.
>>
>> And the last matrix is
>>
>> #[12,] 1 2 3 4 5
>>
>> from which the position [12,1] is selected.
>>
>> So, the resulting entries from this process are 1, 2, 3, 1, 2, 3, 4, 5,
1.
>>
>> Thank you in advance for any additional insight you may provide.
>>
>> Regards,
>> Jorge Velez.-
>>
>>
>>
>> On Tue, Oct 27, 2015 at 4:06 PM, David L Carlson <dcarlson at
tamu.edu>
>> wrote:
>>
>>> I don't see how you are getting the result you provide.
>>>
>>>> m
>>> [,1] [,2] [,3] [,4] [,5]
>>> [1,] 0 0 0 0 0
>>> [2,] 0 0 0 0 0
>>> [3,] 0 0 0 0 0
>>> [4,] 1 2 3 0 0
>>> [5,] 1 2 3 0 0
>>> [6,] 1 2 3 0 0
>>> [7,] 1 2 3 0 0
>>> [8,] 1 2 3 0 0
>>> [9,] 1 2 3 4 0
>>> [10,] 1 2 3 4 0
>>> [11,] 1 2 3 4 5
>>> [12,] 1 2 3 4 5
>>>> t(sapply(1:8, function(x) diag(m[x:12, ])))
>>> [,1] [,2] [,3] [,4] [,5]
>>> [1,] 0 0 0 0 0
>>> [2,] 0 0 3 0 0
>>> [3,] 0 2 3 0 0
>>> [4,] 1 2 3 0 0
>>> [5,] 1 2 3 0 0
>>> [6,] 1 2 3 4 0
>>> [7,] 1 2 3 4 5
>>> [8,] 1 2 3 4 5
>>>
>>> These are all of the diagonals from the 1st through 8th rows. The
first 3
>>> begin with 0 so we leave them out, but then we have 4th: 1, 2, 3;
5th: 1,
>>> 2, 3; 6th: 1, 2, 3, 4, etc so you must have some additional rule in
mind to
>>> get your answer.
>>>
>>> -------------------------------------
>>> David L Carlson
>>> Department of Anthropology
>>> Texas A&M University
>>> College Station, TX 77840-4352
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
Jorge I
>>> Velez
>>> Sent: Tuesday, October 27, 2015 2:44 PM
>>> To: jim holtman
>>> Cc: R-help
>>> Subject: Re: [R] Extract entries from matrix
>>>
>>> Dear Jim,
>>>
>>> Thank you very much for your quick reply.
>>>
>>> I am sorry for the confusion it may have caused, but I messed up
the
>>> indexes in my example. I would like, from the following matrix
"m"
>>>
>>> ## input
>>> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
0L,
>>> 0L, 0L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 0L, 0L, 0L, 3L, 3L,
>>> 3L, 3L, 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L,
>>> 4L, 4L, 4L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 5L, 5L), .Dim =
c(12L,
>>> 5L))
>>>
>>> to obtain
>>>
>>> 1 2 3 1 2 3 4 5 1
>>>
>>> Sure using m[idx] will give the desired result. The problem is
that idx
>>> is
>>> not known and needs to be determined from "m". I would
like to use
>>> something like
>>>
>>> extractDiagonals(m)
>>> ## [1] 1 2 3 1 2 3 4 5 1
>>>
>>> I look forward to your reply. Thanks in advance.
>>>
>>> Best regards,
>>> Jorge Velez.-
>>>
>>>
>>>
>>> On Tue, Oct 27, 2015 at 2:31 PM, jim holtman <jholtman at
gmail.com> wrote:
>>>
>>>> If you want to use the numbers you gave a the index into the
matrix,
>>> then
>>>> you can create a matrix with the values and then index into
'm'. I
>>> don't
>>>> see a '4' in the output example you gave using your
index values:
>>>>
>>>>> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L,
>>>> + 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L,
2L,
>>>> + 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
0L,
>>>> + 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L,
>>>> + 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L,
4L,
>>>> + 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L,
0L,
>>>> + 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,
5L,
>>>> + 5L), .Dim = c(22L, 5L))
>>>>> # create index matrix
>>>>> indx <- matrix(c(4, 1,
>>>> + 5, 2,
>>>> + 6, 3,
>>>> + 7, 1,
>>>> + 8, 2,
>>>> + 9, 3,
>>>> + 10, 1,
>>>> + 11, 2,
>>>> + 12, 3), ncol = 2, byrow = TRUE)
>>>>>
>>>>>
>>>>> m
>>>> [,1] [,2] [,3] [,4] [,5]
>>>> [1,] 0 0 0 0 0
>>>> [2,] 0 0 0 0 0
>>>> [3,] 0 0 0 0 0
>>>> [4,] 1 2 3 0 0
>>>> [5,] 1 2 3 0 0
>>>> [6,] 1 2 3 0 0
>>>> [7,] 1 2 3 0 0
>>>> [8,] 1 2 3 0 0
>>>> [9,] 1 2 3 4 0
>>>> [10,] 1 2 3 4 0
>>>> [11,] 1 2 3 4 5
>>>> [12,] 1 2 3 4 5
>>>> [13,] 1 2 3 4 5
>>>> [14,] 1 2 3 4 5
>>>> [15,] 1 2 3 4 5
>>>> [16,] 1 2 3 4 5
>>>> [17,] 1 2 3 4 5
>>>> [18,] 1 2 3 4 5
>>>> [19,] 1 2 3 4 5
>>>> [20,] 1 2 3 4 5
>>>> [21,] 1 2 3 4 5
>>>> [22,] 1 2 3 4 5
>>>>> indx
>>>> [,1] [,2]
>>>> [1,] 4 1
>>>> [2,] 5 2
>>>> [3,] 6 3
>>>> [4,] 7 1
>>>> [5,] 8 2
>>>> [6,] 9 3
>>>> [7,] 10 1
>>>> [8,] 11 2
>>>> [9,] 12 3
>>>>> m[indx]
>>>> [1] 1 2 3 1 2 3 1 2 3
>>>>
>>>>
>>>> Jim Holtman
>>>> Data Munger Guru
>>>>
>>>> What is the problem that you are trying to solve?
>>>> Tell me what you want to do, not how you want to do it.
>>>>
>>>> On Tue, Oct 27, 2015 at 2:43 PM, Jorge I Velez <
>>> jorgeivanvelez at gmail.com>
>>>> wrote:
>>>>
>>>>> Dear R-help,
>>>>>
>>>>> I am working with a matrix "m" from which I would
like to extract some
>>>>> elements. An toy example is as follows:
>>>>>
>>>>> ## input matrix
>>>>> m <- structure(c(0L, 0L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L,
>>>>> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 0L, 2L, 2L, 2L,
2L,
>>>>> 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
0L,
>>>>> 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L,
>>>>> 3L, 3L, 3L, 3L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 4L, 4L,
4L,
>>>>> 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 0L, 0L, 0L, 0L,
0L,
>>>>> 0L, 0L, 0L, 0L, 0L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,
5L,
>>>>> 5L), .Dim = c(22L, 5L))
>>>>>
>>>>> R> m
>>>>> # [,1] [,2] [,3] [,4] [,5]
>>>>> # [1,] 0 0 0 0 0
>>>>> # [2,] 0 0 0 0 0
>>>>> # [3,] 0 0 0 0 0
>>>>> # [4,] 1 2 3 0 0
>>>>> # [5,] 1 2 3 0 0
>>>>> # [6,] 1 2 3 0 0
>>>>> # [7,] 1 2 3 0 0
>>>>> # [8,] 1 2 3 0 0
>>>>> # [9,] 1 2 3 4 0
>>>>> # [10,] 1 2 3 4 0
>>>>> # [11,] 1 2 3 4 5
>>>>> # [12,] 1 2 3 4 5
>>>>>
>>>>>> From "m", I would like to extract the entries
>>>>>
>>>>> 4, 1
>>>>> 5, 2
>>>>> 6, 3
>>>>> 7, 1
>>>>> 8, 2
>>>>> 9, 3
>>>>> 10, 1
>>>>> 11, 2
>>>>> 12, 3
>>>>>
>>>>> so at the end of applying a function "f" to
"m" I get
>>>>>
>>>>> 1, 2, 3, 1, 2, 3, 4, 1, 2, 3
>>>>>
>>>>>
>>>>> Basically the idea is to extract the diagonal elements
until a zero is
>>>>> found.
>>>>>
>>>>> In the real problem the dimensions of "m" are
much bigger, but this
>>>>> smaller
>>>>> version of "m" illustrate what needs to be done.
>>>>>
>>>>> I would greatly appreciate any ideas on how to do this.
>>>>>
>>>>> Thanks in advance,
>>>>> Jorge Velez.-
>>>>>
>>>>> [[alternative HTML version deleted]]
>>>>>
>>>>> ______________________________________________
>>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and
more, see
>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>> PLEASE do read the posting guide
>>>>> http://www.R-project.org/posting-guide.html
>>>>> and provide commented, minimal, self-contained,
reproducible code.
>>>>>
>>>>
>>>>
>>>
>>> [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more,
see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
> <example.png>______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.