Good morning !
Today I found a strange, for my poor knowledge of R, behaviour of
'which' on a matrix:
HAL9000> str(cluster.matrix)
num [1:227, 1:6300] 2 2 2 2 2 2 2 2 2 2 ...
HAL9000> class(cluster.matrix)
[1] "matrix"
HAL9000> ase <- cluster.matrix[1:5,1:5]
HAL9000> ase
[,1] [,2] [,3] [,4] [,5]
[1,] 2 2 2 0 -2
[2,] 2 2 2 0 -2
[3,] 2 2 2 0 -2
[4,] 2 2 2 0 -2
[5,] 2 2 2 0 -2
HAL9000> ase2 <- matrix(c(2,2,2,2,2)%*%t(c(1,1,1,0,-1)),5,5)
HAL9000> ase2
[,1] [,2] [,3] [,4] [,5]
[1,] 2 2 2 0 -2
[2,] 2 2 2 0 -2
[3,] 2 2 2 0 -2
[4,] 2 2 2 0 -2
[5,] 2 2 2 0 -2
HAL9000> str(ase2)
num [1:5, 1:5] 2 2 2 2 2 2 2 2 2 2 ...
But now:
HAL9000> which(ase2==-2,arr.ind=T)
row col
[1,] 1 5
[2,] 2 5
[3,] 3 5
[4,] 4 5
[5,] 5 5
HAL9000> which(ase==-2,arr.ind=T)
numeric(0)
which(ase=="-2",arr.ind=T)
row col
[1,] 1 5
[2,] 2 5
[3,] 3 5
[4,] 4 5
[5,] 5 5
May be the original matrix 'cluster.matrix' is not
properly a numerical matrix!? But 'str' say num[...] !!??
Some suggestion.
Tks!
A.S.
----------------------------
Alessandro Semeria
Models and Simulations Laboratory
Montecatini Environmental Research Center (Edison Group),
Via Ciro Menotti 48,
48023 Marina di Ravenna (RA), Italy
Tel. +39 544 536811
Fax. +39 544 538663
E-mail: alessandro.semeria at cramont.it
asemeria at cramont.it wrote:> > > > Good morning ! > Today I found a strange, for my poor knowledge of R, behaviour of > 'which' on a matrix: > > HAL9000> str(cluster.matrix) > num [1:227, 1:6300] 2 2 2 2 2 2 2 2 2 2 ... > > HAL9000> class(cluster.matrix) > [1] "matrix" > > HAL9000> ase <- cluster.matrix[1:5,1:5] > > HAL9000> ase > [,1] [,2] [,3] [,4] [,5] > [1,] 2 2 2 0 -2 > [2,] 2 2 2 0 -2 > [3,] 2 2 2 0 -2 > [4,] 2 2 2 0 -2 > [5,] 2 2 2 0 -2 > > HAL9000> ase2 <- matrix(c(2,2,2,2,2)%*%t(c(1,1,1,0,-1)),5,5) > > HAL9000> ase2 > [,1] [,2] [,3] [,4] [,5] > [1,] 2 2 2 0 -2 > [2,] 2 2 2 0 -2 > [3,] 2 2 2 0 -2 > [4,] 2 2 2 0 -2 > [5,] 2 2 2 0 -2 > > HAL9000> str(ase2) > num [1:5, 1:5] 2 2 2 2 2 2 2 2 2 2 ... > > But now: > > HAL9000> which(ase2==-2,arr.ind=T) > row col > [1,] 1 5 > [2,] 2 5 > [3,] 3 5 > [4,] 4 5 > [5,] 5 5 > > HAL9000> which(ase==-2,arr.ind=T) > numeric(0) > > which(ase=="-2",arr.ind=T) > row col > [1,] 1 5 > [2,] 2 5 > [3,] 3 5 > [4,] 4 5 > [5,] 5 5 > > > May be the original matrix 'cluster.matrix' is not > properly a numerical matrix!? But 'str' say num[...] !!?? > Some suggestion.My guess is that cluster.matrix, hence ase, has been generated in some calculation, and its numerical floating point representation is a bit off the expected integer. Use identical(), all.equal() and friends to analyse it. Uwe Ligges> Tks! > > > A.S. > > ---------------------------- > > Alessandro Semeria > Models and Simulations Laboratory > Montecatini Environmental Research Center (Edison Group), > Via Ciro Menotti 48, > 48023 Marina di Ravenna (RA), Italy > Tel. +39 544 536811 > Fax. +39 544 538663 > E-mail: alessandro.semeria at cramont.it > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! R-project.org/posting-guide.html