Dear R users,
i want to check matrices if they are identical when i change the rows or the
columns or the signs of the one or more columns
isomorphic <- 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)
}
example 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)
the programme works perfeclty when it checks the rows and the columns seperatly
and when it check the signs seperatly
but it doesnt work correcly when i have the combination of the rows, columns,
signs
ps in the above patrices only the a2 is Truly False.
all the are must be true
and the problem i have is a5 because i change signs in last columns and the
order of the first 2 rows
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