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Comparing line in one file to multiple lines in another/FORTRAN

  1. Oct 19, 2013 #1
    Hi y'all

    I am trying to compare two files, so make one line from one file be compared to alll the lines in the other file until it finds a match where the difference is less than 0.003.

    This what I had thought of, but I still think it is just comparing line by line, instead of one line to all the other lines. Any suggestions would be great!

    This is what I have so far:


    program matchCoords
    implicit none

    real :: xcoord1, ycoord1,x1,y1,mag1,merr1,sharp1,chi1
    real :: xcoord2, ycoord2,x2,y2,mag2,merr2,sharp2,chi2
    real, parameter :: arcsec = 0.0003
    character (len=50) :: inputfile1, inputfile2, outputfile
    integer :: i

    !Open input file as unit 15
    write(*,*) 'Enter inputfile #1:'
    read(*,*) inputfile1
    write(*,*) 'Enter inputfile #2'
    read(*,*) inputfile2
    write(*,*) 'Enter output file name:'
    read(*,*) outputfile
    open(unit=15, file=inputfile1, status='old')
    open(unit=16, file=inputfile2, status='old')
    open(unit=17, file=outputfile, status='new')

    do i=0,37200
    read(16,*) xcoord2, ycoord2,x2,y2,mag2,merr2,sharp2,chi2
    do j=0,37000
    read(15,*) xcoord1(j), ycoord1(j),x1,y1,mag1,merr1,sharp1,chi1

    if(ABS(xcoord1(j)-xcoord2).le.arcsec.and.ABS(ycoord1(i)-ycoor&
    &d2).le.arcsec) then

    write(17,*) xcoord1(j),ycoord1(j),x1,y1,mag1,merr1,&
    &sharp1,chi1,xcoord2,ycoord2,x2,y2,&
    &mag2,merr2,sharp2,chi2
     
  2. jcsd
  3. Oct 19, 2013 #2
    You have not declared any arrays, yet, you are using indices with xcoord1 and ycoord1.

    I don't see the 'end do' lines nor the file rewind...from what I can see, once you go thru the inner loop once (and you get to the end of that file), you will not be able to do that again without a rewind on that file.

    I think it is best to simply read the entire array of data, at least, the one that is going to be in the inner loop; in the outer loop, you can get away by just reading one line at a time until the end of file.

    So declare arrays for your xxxx1 variables long enough to read the entire file; then, go ahead and do the nested do loop...there will only be need to read a line in the outer loop...in the inner one, you can skip the read statement and go straight to the comparison (using array indices).
     
  4. Oct 20, 2013 #3
    Thank you so much, gsal, for taking the timel! I will try that today!
     
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