Thanks, I will have a look at this.
Is there some interest to have this in base?
Davide
On Wednesday, March 11, 2015 at 1:38:34 PM UTC, Mauro wrote:
>
> Have a look at the permute! function in julia:
> @less permute!([1,2], [1,2])
>
> Modifying it to
>
> function permute!!{T<:Integer}(a, i, p::AbstractVector{T})
> count = 0
> start = 0
> while count < length(a)
> ptr = start = findnext(p, start+1)
> temp = a[i,start]
> next = p[start]
> count += 1
> while next != start
> a[i,ptr] = a[i,next]
> p[ptr] = 0
> ptr = next
> next = p[next]
> count += 1
> end
> a[i,ptr] = temp
> p[ptr] = 0
> end
> a
> end
>
> should work (untested). Note that permuting a column should be faster
> though as julia matrices are column-major.
>
> On Wed, 2015-03-11 at 13:49, Davide Lasagna <lasagn...@gmail.com
> <javascript:>> wrote:
> > Hi,
> >
> >
> > permute!(v, p) permutes the elements of v according to the permutation
> > vector p.
> >
> > Is there any equivalent built in function for permuting rows of a
> matrix?
> > Given the memory layout of julia matrices it should not be too difficult
> to
> > have a similar function for matrices as well.
> >
> > Thanks,
> >
> > Davide
>
>
