i have this matrices
a<-matrix(c(1,1,1,1,-1,-1,-1,-1,-1,1,1,1),ncol=4,byrow=T)
a1<-matrix(c(-1,-1,-1,-1,1,1,1,1,-1,1,1,1),ncol=4,byrow=T)
a2<-matrix(c(1,1,1,1,-1,-1,-1,-1,1,1,1,1),ncol=4,byrow=T)
a3<-matrix(c(1,1,1,1,-1,-1,-1,-1,1,1,1,-1),ncol=4,byrow=T)
a4<-matrix(c(1,1,1,-1,-1,-1,-1,1,-1,1,1,-1),ncol=4,byrow=T)
a5<-matrix(c(1,1,1,-1,-1,-1,-1,1,1,-1,1,-1),ncol=4,byrow=T)
a6<-matrix(c(1,1,1,1,-1,-1,-1,-1,1,-1,1,1),ncol=4,byrow=T)
a7<-matrix(c(1,1,-1,-1,-1,-1,1,1,-1,1,-1,-1),ncol=4,byrow=T)
and this programme
isomorphic1 <- function (m1, m2) {
combs.c <- combn(ncol(m1), 2)
nc <- ncol(combs.c)
ind.c <- vector("logical", nc)
for (i in 1:nc) {
m <- m1
m[, combs.c[, i]] <- m[, rev(combs.c[, i])]
ind.c[i] <- all(m == m2)
}
combs.r <- combn(nrow(m1), 2)
nr <- ncol(combs.r)
ind.r <- vector("logical", nr)
for (i in 1:nr) {
m <- m1
m[combs.r[, i], ] <- m[rev(combs.r[, i]), ]
ind.r[i] <- all(m == m2)
}
ind.sgn <- lapply(1:ncol(m1), combn, x = ncol(m1))
ind.sgn <- unlist(lapply(ind.sgn, function (ind) {
ncc <- ncol(ind)
out <- vector("logical", ncc)
for (l in 1:ncc) {
m <- m1
m[, ind[, l]] <- -m[, ind[, l]]
out[l] <- all(m == m2)
}
out
}))
any(ind.c, ind.r, ind.sgn)
}
in the above matrices only a2 is trully false
all the others must be true
it cant check simultaneously the ind.c, ind.r ind.sgn
as a5 has ind.c and ind.sgn simultaneously TRUE
ind.c & ind.sgn are False & false
