在 Fortran 中读取具有未知行数的文件 [英] Read a file with an unknown number rows in Fortran
问题描述
英雄我使用的新代码.我已经尝试过了,如果我先声明了它,它就可以工作,这不是我想要的.我需要知道总行数(n) 然后在我的模拟中使用该数字.但是,在变量声明中,我需要在读取数据之前减小 xy(n),如果这样做,代码将不会运行.
Heroes the new code I used. I have tried this, and it works if I have n declared first, which is not what I want. I need to know the total number of rows (n) and use that number afterward in my simulation. However, in variable declaration I need to have the diminution of my xy(n) before reading the data and if I do that, the code does not run.
数据文件是两列随机模拟的正常数据
the data file is two column of randomly simulated normal data
这样说吧
1 3
2 4
3 6
4 8
5 9
6 8
7 1
8 9
99 88
我尝试了以下代码来确定 n 但它不起作用!
I tried the following code to determine n but it did not work!
program reading
implicit none
integer,allocatable :: a(:,:)
integer :: pair(2)
integer :: unit, n, io,k
!!!variable declaration
real, dimension(1:n)::x,y
integer:: T, I1, I2, I3, i, j, dist
open(2, file = 'xyBVNData_R.txt', status = 'old', action = 'read')
n = 0
DO
READ(2,*,iostat=io)
IF (io/=0) EXIT
n = n + 1
END DO
CLOSE (2)
print*, n
DO i=1,n!!!
DO j=1,n!!
dist=0.0
DIST = dist+(sqrt((x(i)-x(j))**2 + (y(i)-y(j))**2))
ENDDO
ENDDO
!!! writing and saving
Do i= 1, n
write(*,*) i, x(i)
ENDDO
end program reading
推荐答案
不能声明维度未知dimension(1:n)"的变量.
You can't declare variables with unknown dimension "dimension(1:n)".
此程序首先读取文件以确定行数:
This program first reads the file to determine the number of rows:
program reading
implicit none
! variable declaration
real, dimension(:) ,allocatable :: x ,y
real :: dist
integer:: i, j ,n ,io
open(2, file = 'xyBVNData_R.txt', status = 'old', action = 'read')
n = 0
DO
READ(2,*,iostat=io)
IF (io/=0) EXIT
n = n + 1
END DO
print*, n
allocate( x(n) ,y(n) )
rewind(2)
DO i =1,n
READ(2,*) x(i),y(i)
END DO
dist=0.0
DO i=1,n
DO j=1,n
dist = dist + sqrt( (x(i)-x(j))**2 + (y(i)-y(j))**2 )
END DO
END DO
! writing and saving
DO i= 1, n
write(*,*) i, x(i)
END DO
end program reading
另一种选择(Fortran 2003),它通过在读取新行时添加新元素来重新分配数组 x
和 y
:
Another alternative (Fortran 2003), it reallocates the arrays x
and y
by adding the new element when a new line is read:
program reading
implicit none
! variable declaration
real, dimension(:) ,allocatable :: x ,y
real :: dist ,x_tmp ,y_tmp
integer:: i, j ,n ,io
open(2, file = 'xyBVNData_R.txt', status = 'old', action = 'read')
n = 0
allocate( x(0) ,y(0) )
DO
READ(2,*,iostat=io) x_tmp,y_tmp
x = [x,x_tmp]
y = [y,y_tmp]
IF (io/=0) EXIT
n = n + 1
END DO
print*, n
dist=0.0
DO i=1,n
DO j=1,n
dist = dist + sqrt( (x(i)-x(j))**2 + (y(i)-y(j))**2 )
END DO
END DO
! writing and saving
DO i= 1, n
write(*,*) i, x(i)
END DO
end program reading
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