I try to read and re-write a matrix that has only a particular series of columns. For instance I have an 11 x n matrix and I want to rewrite it in a 2 x n matrix with only columns 2 and 3.
program fluxXYlambda
implicit none
INTEGER*8::n,i
REAL*8,ALLOCATABLE::dati(:,:)
open(10,file='test.txt')
n=0
do
read(10,*,end=100)
n=n+1
end do
100 continue
rewind(10)
allocate(dati(11,n))
open(12,file='coordXY.txt')
do i=1,n
read(10,*) dati(4,i),dati(5,i)
write(12,*) dati(4,i),dati(5,i)
end do
end program flussiXYlambda
The file coordXY.txt is created but is empty.
Finally i solve the problem thanks to #francescalus.
The command read(10,*) dati(1:5,i) read the matrix dati till the column 5 and than i can save particular columns of it. Thanks a lot !
Related
I'm using this code below to generate a file with i number (i=200 for instance) of rows, but the first and the second rows are fixed and I just want to create another i rows using a random extraction in a sphere of unitary radius in Fortran. Each row should start with m1 and then 6 random numbers between a range [0,1].
program InputGen
implicit none
integer :: i,n,j
character(len=500) :: firstLine, secondLine
real *8 :: m1
real:: r(10)
m1=1.d0
firstLine='3 5 1.d-4 1.d5 0.e-3 0.0 1. 0.1 0.e0 1'
secondLine='4.d6 0. 0. 0. 0. 0. 0. '
call random_seed()
call random_number(r)
open(unit=100, file='INPUT.TXT',Action='write', Status='replace')
write(100,'(A)') trim(firstLine)
write(100,'(A)') trim(secondLine)
do i=1,200
write(100,'(A)') '',m1,' ',(r(n),n=1,10),
' ',(r(n),n=1,10),'0.0',&
' ',(r(n),n=1,10),&
' ',(r(n),n=1,10),'0.0'
end do
write(*,*) 'Input file generated.'
write(*,*) 'Press Enter to exit...'
read(*,*)
end program InputGen
The first and second lines create perfectly, but the other rows in the loop not.
You did not tell us what is wrong (how the problem exhibits), but I suspect the format is incorrect. You are just specifying (A), but you have a mixed output list with strings and numbers.
You can just use a simple general format like (*(g0)) that will apply the generic g0 format to all items in the input list. You will want to add some manual spaces (although you already have some) in the input list to avoid joining two unrelated output items on the line.
Or you can just follow the input list and add a specific format for each item, like (a,1x,f12.6,a,10(f12.6,1x),a ... and so on. Adjust as needed, especially the spaces (either keep them as ' ' with the a descriptor, or use the 1x descriptor.
You are also currently writing the same r all the time. You should generate more numbers and re-generate them an each loop iteration
real:: r(40)
do i=1,200
call random_number(r)
write(100,'(*(g0))') '',m1,' ',r(1:10),
' ',r(11:20),'0.0',&
' ',r(21:30),&
' ',r(31:40),'0.0'
end do
This does not do anything with points in a sphere or anything similar, this just prints random numbers. I hope that is clear.
I am trying to read a file called "syerasg.txt" in Fortran90. This text file includes panel data on 91 variables (columns) for 8984 individuals for 16 years (143 744 rows). This variables are divided in 7 groups and this groups are divided in 13 subgroups. I am trying to read this file with the following code:
PROGRAM main
IMPLICIT NONE
INTEGER, PARAMETER :: p=8984, tf=16, sem=53, emp=7, gap=13
INTEGER :: r, t, j, m, g, x, i, IOstatus
INTEGER, DIMENSION (p,tf,emp) :: yemp
INTEGER, DIMENSION (p,tf,emp,gap) :: gaps
OPEN(UNIT=4, FILE='syearsg.txt',STATUS='old') !start gap years
DO i=1,p
DO t=1,tf
DO j=1,emp
IF (j==1) THEN
READ(4,*)(gaps(i,t,j,g),g=1,13)
ELSE IF (j==2) THEN
READ(4,*)(gaps(i,t,j,g-13),g=14,26)
ELSE IF (j==3) THEN
READ(4,*)(gaps(i,t,j,g-26),g=27,39)
ELSE IF (j==4) THEN
READ(4,*)(gaps(i,t,j,g-39),g=40,52)
ELSE IF (j==5) THEN
READ(4,*)(gaps(i,t,j,g-52),g=53,65)
ELSE IF (j==6) THEN
READ(4,*)(gaps(i,t,j,g-65),g=66,78)
ELSE IF (j==7) THEN
READ(4,*)(gaps(i,t,j,g-78),g=79,91)
END IF
END DO
END DO
END DO
CLOSE(4)
END PROGRAM main
When, running the code I get the following message:
Fortran runtime error: End of file
Any ideas on how to solve this?
Your loop nest issues 1,006,208 (that is p*tf*emp) read statements. It's no surprise that the program runs past the end of a file with only 143,744 lines. read reads the values it is asked to read, then skips to the start of the next line ready for the next read.
You might be able to fix your program by fiddling around with non-advancing input, ie telling the read statements not to skip to the start of the next line. But it would be easier not to.
From what you write you should only be issuing p*tf read statements, then reading a single line containing 91 elements, then distributing those elements into gaps as your logic demands.
You might revise your code to something like this (untested and not very carefully checked)
INTEGER, DIMENSION(91) :: workvec
...
DO i=1,p
DO t=1,tf
READ(4,*) workvec
gaps(i,t,1,1:13) = workvec( 1:13)
gaps(i,t,2,1:13) = workvec(14:26)
...
END DO
END DO
Suppose I have the matrix c(i,j). I want to write it on the screen on oldest Fortran77 language with three signs after comma. I write
do i=1,N
write(*,"(F8.3)") ( c(i,j), j=1,N )
end do
but the output is in the form
c(1,1)
c(1,2)
...
c(1,10) c(2,1)
c(2,2)
...
Finally, I may simply write
do i=1,N
write(*,*) ( c(i,j), j=1,N )
end do
and then the output is like the matrix, but, of course, it is not formatted.
How to get the correct output in Fortran77?
An edit. It seems that one of solutions is to write
do i=1, N
do j=1, N
write(*,'(F9.3,A,$)') c(i,j), ' '
end do
write(*,*) ' '
end do
Your format only specifies a single float but you actually want to write N per line.
A fairly general solution for this simple case would be something like
program temp
implicit none
integer, parameter :: N=3
real, dimension(N,N) :: c
integer :: i,j
character(len=20) :: exFmt
c = 1.0
write(exFmt,'("(",I0,"(F8.3))")') N
do i=1,N
write(*,exFmt) (c(i,j), j=1,N)
end do
end program
This will make exFmt be '(3(F8.3))', which specifies printing three floats (note you probably really want '(3(F8.3," "))' to explicitly include some spacing).
Note some compilers will allow for exFmt to be just '(*(F8.3))'. This is part of the fortran 2008 specification so may not be provided by all compilers you have access to. See here for a summary of compiler support (see Unlimited format item, thanks to HighPerformanceMark for this)
Finally an easy bodge is to use a format statment like '(1000(F8.3))' where 1000 is larger than you will ever need.
I have opened a file to write a number. I have to write the number at the end of the file so
how to go to the last line to write on it?
You should open the file with
open(..., position="append",...)
Alternatively, you can inquire for the size of the file
inquire(...,size=some_integer_variable,...)
then if the file is a direct access file, you can use this size to calculate the record number of the final record. Alternatively, if the access mode is "stream", you can use
write(..., pos=some_integer_variable)
to write starting at the end of the file.
I've been using the same trick for years, and would be interested in a more elegant way but I can propose you the following method. Note that it is less and less efficient as the file increases in number of lines. Note also that this part of code could endup in an elegant module dedicated to playing with input/output.
Open your file
open(11, file='monfichier')
Compute how many lines there are in your file
nbline = 0 ! should have been declared as an integer
do while(.true.)
read(11,*,iostat=ios) ! ios should have been declared as an integer
if( ios > 0 ) then
stop 'problem somewhere'
else if( ios < 0 ) then ! end of file is reached
exit
else
nbline = nbline + 1
end if
end do
close(11)
at this step, you have the total number of lines stored in variable nbline.
If you want to print something at the Nth line before the last line, then
open(11, file='monfichier')
do i = 1, nbline - N ! see my nota bene at the end of my answer; i and N are integers
read(11,*)
end do
write(11,*)'hello world'
Et voilà !
N.B. : Please be carefull in the way you count for nbline-N or nbline-(N-1), depending on exactly what you want.
subroutine to_last_rec (luout)
! purpose: position to last record of file
implicit none
integer :: luout
logical :: ende
! first executable statement
ende = .FALSE.
do while ( .NOT. ende)
read (luout,*,end=100)
enddo
100 return
end subroutine to_last_rec
PROGRAM example
IMPLICIT NONE
INTEGER :: ierr
OPEN(UNIT=13,FILE="ex.dat")
CALL FSEEK(13, 0, 2, ierr)
! DO WHATEVER YOU WANT THEN
CLOSE(13)
END PROGRAM example
the call to fseek goes to the end of the file ( used like that, check the usage http://docs.oracle.com/cd/E19957-01/805-4942/6j4m3r8ti/index.html)
I am using FORTRAN to read in data from an ASCII text file. The file contains multiple data values per line but the number of values per line is not constant.
101.5 201.6 21.4 2145.5
45.6 21.2
478.5
...
Normally after a read statement, Fortran would go to the next line. What I want to be able to do is read one data value at a time. If it hits the end of the line, it should just continue reading on the next line. Is this possible?
As pointed out by IRO-bot in their comment to your question, the answer has already been given by M.S.B. Below I have merely provided some code illustrating that answer (as M.S.B.'s post contained none):
program test
character(len=40) :: line
integer :: success, i, indx, prev, beginning
real :: value
open(1,file='test.txt')
do
read(1,'(A)',iostat=success) line
if (success.ne.0) exit
prev = 1
beginning = 1
do i=1,len(line)
! is the current character one out of the desired set? (if you
! have got negative numbers as well, don't forget to add a '-')
indx = index('0123456789.', line(i:i))
! store value when you have reached a blank (or any other
! non-real number character)
if (indx.eq.0 .and. prev.gt.0) then
read(line(beginning:i-1), *) value
print *, value
else if (indx.gt.0 .and. prev.eq.0) then
beginning = i
end if
prev = indx
end do
end do
close(1)
end program test
When running this program using the sample lines you provided the output is
101.5000
201.6000
21.40000
2145.500
45.60000
21.20000
478.5000
I hope you will find this helpful.