Manipulating Arrays of Same Number of Elements but with Different Dims
in [Fortran]
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From: monir on 18 Feb 2010 11:54 Hello; 1) I've the following 1D arrays written in a sequential data file: np = nx * nr * nt do i =1, nrecords write (80) (x(m), r(m), t(m), m=1, np) write (80) (vx(m), vr(m), vt(m), m=1, np) end do 2) Somewhere in the program, I'd like to read all the records and assign an index to each one. THEN, for a given record, convert each array variable to its nx, nr, nt dims. For example: (with arrays x, r, t DO not differ in this exercise; but the v's arrays DO) do ii =1, nrecord Read (80) (((xb(i,j,k), rb(i,j,k),tb(i,j,k), k=1, nt), j=1, nr), i=1, np) Read (80) (vxi(ii,m), vri(ii,m), vti(ii,m), m=1, np) end do THEN: For a desired record, say, ii=5, I need to convert: vxi(5,m), vri(5,m), vti(5,m), m=1, np to: vxx(i,j,k), vrr(i,j,k), vtt(i,j,k), i=1, nx, j=1,nr, k=1,nt Can this be done without using 4D arrays or Equivalence (F77/g95) ?? Regards. Monir
From: e p chandler on 18 Feb 2010 16:11 On Feb 18, 11:54 am, monir <mon...(a)mondenet.com> wrote: > Hello; > > 1) I've the following 1D arrays written in a sequential data file: > np = nx * nr * nt > do i =1, nrecords > write (80) (x(m), r(m), t(m), m=1, np) > write (80) (vx(m), vr(m), vt(m), m=1, np) > end do > > 2) Somewhere in the program, I'd like to read all the records and > assign an index to each one. THEN, for a given record, convert each > array variable to its nx, nr, nt dims. > > For example: > (with arrays x, r, t DO not differ in this exercise; but the v's > arrays DO) > do ii =1, nrecord > Read (80) (((xb(i,j,k), rb(i,j,k),tb(i,j,k), k=1, nt), j=1, nr), > i=1, np) > Read (80) (vxi(ii,m), vri(ii,m), vti(ii,m), m=1, np) > end do > > THEN: > For a desired record, say, ii=5, I need to convert: > vxi(5,m), vri(5,m), vti(5,m), m=1, np > to: > vxx(i,j,k), vrr(i,j,k), vtt(i,j,k), i=1, nx, j=1,nr, k=1,nt > > Can this be done without using 4D arrays or Equivalence (F77/g95) ?? > > Regards. > Monir How was the data written to the sequential data file? What was the order of the subscripts for x, r and t used when the file was written? Just read the data file one record at a time into temporary variables. Next figure out what the I,J and K indices must be. Then assign each value to FOO(I,J,K), BAR(I,J,K), BAZ(I,J,K) etc. --- e
From: monir on 18 Feb 2010 18:39 On Feb 18, 4:11 pm, e p chandler <e...(a)juno.com> wrote: > On Feb 18, 11:54 am, monir <mon...(a)mondenet.com> wrote: > > Monir > > e p chandler wrote: > How was the data written to the sequential data file? What was the > order of the subscripts for x, r and t used when the file was written? > The data was written to the sequential file with "t" changing faster, then "r", and then "x". The same for vt, vr, vx. Regards. Monir
From: e p chandler on 18 Feb 2010 20:16 "monir" <monirg(a)mondenet.com> wrote in message news:f4014600-20a5-4865-a1a6-7ffa3e7595cd(a)c5g2000vbh.googlegroups.com... On Feb 18, 4:11 pm, e p chandler <e...(a)juno.com> wrote: > On Feb 18, 11:54 am, monir <mon...(a)mondenet.com> wrote: > > Monir > > e p chandler wrote: > How was the data written to the sequential data file? What was the > order of the subscripts for x, r and t used when the file was written? > The data was written to the sequential file with "t" changing faster, then "r", and then "x". The same for vt, vr, vx. Regards. Monir But you seem to want to read it back in as var(x_index,r_index,t_index). Unfortunately in Fortran, the first subscript varies the most rapidly, not the last. So you have written out the data as a higher dimensional transpose of the natural order in which Fortran would want to read it. --- e
From: monir on 19 Feb 2010 14:42
On Feb 18, 8:16 pm, "e p chandler" <e...(a)juno.com> wrote: > "monir" <mon...(a)mondenet.com> wrote in message > > On Feb 18, 4:11 pm, e p chandler <e...(a)juno.com> wrote: > > But you seem to want to read it back in as var(x_index,r_index,t_index). > Unfortunately in Fortran, the first subscript varies the most rapidly, not > the last. So you have written out the data as a higher dimensional transpose > of the natural order in which Fortran would want to read it. > > --- e That's correct, and would've caused serious problems if the write/read arrays are multidimensional. The difference here is that I've the arrays written and read as 1D, and simply assigned each read element to a particular position in 2D or 3D arrays, as the case may be. The answer to my inquiry in the OP appears to be much simpler than I had originally thought. Here's what appears to be working fine for me: Data is written to the sequential file with "t" changing faster, then "r", and then "x". Same for vt, vr, vx. !......................... !The 1D arrays are written in a continuous sequence np = nx * nr * nt do i =1, nrecords Write (80) (x(m), r(m), t(m), m=1, np) Write (80) (vx(m), vr(m), vt(m), m=1, np) end do !......................... !Read the 1D arrays and in the process assign each read element to 2D and 3D arrays; as the case may be !Arrays x, r, t DO not differ in this example from record to record, while the v's arrays DO do ii =1, nrecords Read (80) (((xb(i,j,k), rb(i,j,k),tb(i,j,k), k=1,nt), j=1,nr), i=1,nx) Read (80) (vxi(ii,m), vri(ii,m), vti(ii,m), m=1,np) end do !......................... !For a desired record index "ind", convert the 2D "v" arrays to 3D "v" arrays with subscripts i=1,nx, j=1,nr, k=1,nt !consistent with the written data ind = 5 kount = 0 do i=1, nx do j=1, nr do k=1, nt kount = kount+1 vxx(i,j,k) = vxi(ind,kount) vrr(i,j,k) = vri(ind,kount) vtt(i,j,k) = vti(ind,kount) end do I'm sure you experts can easily accomplish same in a more compact and more efficient way, but ... Any comments ?? Regards. Monir |