I am trying to define a array of arrays. I have defined:
integer,dimension(2,2):: &
x=reshape(source= (/0,1,1,0/), shape=(/2,2/)), &
y=reshape(source= (/1,0,0,1/), shape=(/2,2/)), &
z=reshape(source= (/1,1,1,1/), shape=(/2,2/))
I want to define an array, say, s(3), of which, (x/y/z) are components, i.e.
s(1)=x
s(2)=y
and s(3)=z
how can I achieve that?
The simplest approach might be to define s as a rank-3 array, perhaps
integer, dimension(3,2,2) :: s
and then you can write statements such as
s(1,:,:) = x
s(2,:,:) = y
...
This is the 'natural' way to implement an array of arrays in Fortran. An alternative, which might appeal to you more would be something like:
type :: twodarray
integer, dimension(2,2) :: elements
end type twodarray
type(twodarray), dimension(3) :: s
s(1)%elements = x
If you don't like the wordiness of s(1)%elements = x you could redefine the operation = for your type twodarray, I don't have time right now to write that code for you.
You can always use pointers (in Fortran 95)
program main
implicit none
type :: my_type
integer, pointer :: my_size(:) ! F95
!integer, allocatable :: my_size(:) ! F95 + TR 15581 or F2003
end type my_type
type(my_type), allocatable :: x(:)
allocate(x(3))
allocate(x(1)%my_size(3))
allocate(x(2)%my_size(2))
allocate(x(3)%my_size(1))
print*, x(1)%my_size
print*, x(2)%my_size
print*, x(3)%my_size
deallocate(x(3)%my_size, x(2)%my_size, x(1)%my_size)
deallocate(x)
end program main
It will print
0 0 0
0 0
0
The following is a complete program that uses “(re-)allocation on assignment”, which makes dynamic arrays be more like variables in a dynamically typed language.
program main
implicit none
integer,dimension(2,2):: &
x=reshape(source= (/0,1,1,0/), shape=(/2,2/)), &
y=reshape(source= (/1,0,0,1/), shape=(/2,2/)), &
z=reshape(source= (/1,1,1,1/), shape=(/2,2/))
type :: my_type
integer, allocatable :: component(:,:)
end type my_type
type(my_type) :: s(3)
s(1)%component=x
s(2)%component=y
s(3)%component=z
print*, s(1)%component
print*, s(2)%component
print*, s(3)%component
end program main
It outputs:
0 1 1 0
1 0 0 1
1 1 1 1
