!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!	File name: giannopoulos.f95			!!
!!
!!	Giorgos Giannopoulos / Date: 16/6/2019	!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

program giannopoulos
implicit none

	integer nlines 		! number of lines of input file
	integer i
	integer valid 		! number of valid data
	integer missing 	! number of missing data
	real mo 	! Mean value
	real s2		! variance s^2
	real s 		! standard deviation s
	real, dimension (:), allocatable :: array	! array to store valid data, dynamically allocated
	character(len=30)	:: temp		! used to read file line by line and count *(missing data)
	character(len=30)	:: date
	integer stat 	! used in opening of input file

	mo = 0.0;
	s2 = 0.0;

	! find # of lines in input file
	nlines = 0
	missing = 0
	open(24, file = 'giannopoulos.data', IOSTAT=stat, status = 'old')
	if (stat .ne. 0) then 		! check if file exists
            write(*,*) "giannopoulos.data cannot be opened"
            stop 1		! file doesn texist , terminate
    end if
	do
		read(24,'(A)',iostat=stat) temp

		if (stat/=0) then
	       	exit	! end of file
        end if
        print*, temp
        if ( temp .eq. ' *' ) then
        	missing = missing+1		!case of missing data
        end if

		nlines = nlines + 1
	end do
	print*, nlines
	valid = nlines-2-missing	! number of valids = total - first 2 lines - missing data

	! allocate memory
	allocate ( array(valid) )
	rewind(24)	! to be able to read file from start again
	read(24,*)	! avoid first line, name of file
	read(24,*)	! avoid second line, date

	! read valid lines and store data in array
	do i = 1, valid
		read(24,*) array(i)
        print*, array(i)
		mo = mo + array(i)
	end do
	close(24)

	mo = mo/valid 	! estimate mean value
	do i = 1, valid
		s2 = s2 + (array(i)-mo)*(array(i)-mo)
	end do
	s2 = s2/(valid-1) 	! estimate variance
    s = 0.0
	s = sqrt(s2) 		! Standard deviation

	call fdate(date)
	! print output on screen
	print*, "---------------------------------------------"
	print*, "Giorgos Giannopoulos / NTUA"
	print*, "Date / Time	", date
	print*, "File Name:	giannopoulos.f95"
	print*, "---------------------------------------------"
	print*, "Mean value:			", mo
	print*, "Variance:			", s2
	print*, "Standard deviation:		", s
	print*, "Number of missing data:", missing
	print*, "Number of valid data:	", valid
	print*, "---------------------------------------------"

	! print output on OutputFile.data
	open(25, file = 'OutputFile.data', status = 'replace')
	write(25,'(a)') "---------------------------------------------"
	write(25,'(a)') "Giorgos Giannopoulos / NTUA"
	write(25,'(a)') "Date / Time	", date
	write(25,'(a)') "File Name:	giannopoulos.f95"
	write(25,'(a)') "---------------------------------------------"
	write(25,*) "Mean value:			", mo
	write(25,*) "Variance:			", s2
	write(25,*) "Standard deviation:		", s
	write(25,*) "Number of missing data:", missing
	write(25,*) "Number of valid data:	", valid
	write(25,'(a)') "---------------------------------------------"
	close(25)

	! free allocated memory
	deallocate (array)
end program giannopoulos