Manual Reference Pages - count (3fortran)
NAME
COUNT(3) - [ARRAY:REDUCTION] Count true values in an array
SYNOPSIS
result = count(mask [,dim] [,kind] )
integer(kind=KIND) function count(mask, dim, KIND )logical(kind=**),intent(in) :: mask(..) integer(kind=**),intent(in),optional :: dim integer(kind=**),intent(in),optional :: KIND
CHARACTERISTICS
o a kind designated as ** may be any supported kind for the type o MASK is a logical array of any shape and kind. o If DIM is present, the result is an array with the specified rank removed. o KIND is a scalar integer constant expression valid as an integer kind o The return value is of default integer type unless KIND is specified to declare the kind of the result.
DESCRIPTION
COUNT(3) counts the number of .true. elements in a logical MASK, or, if the DIM argument is supplied, counts the number of elements along each row of the array in the DIM direction. If the array has zero size or all of the elements of MASK are false, then the result is 0.
OPTIONS
o MASK : an array to count the number of .true. values in o DIM : specifies to remove this dimension from the result and produce an array of counts of .true. values along the removed dimension. If not present, the result is a scalar count of the true elements in MASK the value must be in the range 1 <= dim <= n, where n is the rank(number of dimensions) of MASK. The corresponding actual argument shall not be an optional dummy argument, a disassociated pointer, or an unallocated allocatable.
o KIND : An integer initialization expression indicating the kind parameter of the result.
RESULT
The return value is the number of .true. values in MASK if DIM is not present.
If DIM is present, the result is an array with a rank one less than the rank of the input array MASK, and a size corresponding to the shape of ARRAY with the DIM dimension removed, with the remaining elements containing the number of .true. elements along the removed dimension.
EXAMPLES
Sample program:
program demo_count implicit none character(len=*),parameter :: ints=’(*(i2,1x))’ ! two arrays and a mask all with the same shape integer, dimension(2,3) :: a, b logical, dimension(2,3) :: mymask integer :: i integer :: c(2,3,4)Results:print *,’the numeric arrays we will compare’ a = reshape( [ 1, 2, 3, 4, 5, 6 ], [ 2, 3 ]) b = reshape( [ 0, 7, 3, 4, 5, 8 ], [ 2, 3 ]) c = reshape( [( i,i=1,24)], [ 2, 3 ,4]) print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print * print ’(3i3)’, b(1,:) print ’(3i3)’, b(2,:) ! ! basic calls print *, ’count a few basic things creating a mask from an expression’ print *, ’count a>b’,count(a>b) print *, ’count b<a’,count(a<b) print *, ’count b==a’,count(a==b) print *, ’check sum = ’,count(a>b) + & & count(a<b) + & & count(a==b).eq.size(a) ! ! The common usage is just getting a count, but if you want ! to specify the DIM argument and get back reduced arrays ! of counts this is easier to visualize if we look at a mask. print *, ’make a mask identifying unequal elements ...’ mymask = a.ne.b print *, ’the mask generated from a.ne.b’ print ’(3l3)’, mymask(1,:) print ’(3l3)’, mymask(2,:) ! print *,’count total and along rows and columns ...’ ! print ’(a)’, ’number of elements not equal’ print ’(a)’, ’(ie. total true elements in the mask)’ print ’(3i3)’, count(mymask) ! print ’(a)’, ’count of elements not equal in each column’ print ’(a)’, ’(ie. total true elements in each column)’ print ’(3i3)’, count(mymask, dim=1) ! print ’(a)’, ’count of elements not equal in each row’ print ’(a)’, ’(ie. total true elements in each row)’ print ’(3i3)’, count(mymask, dim=2) ! ! working with rank=3 ... print *, ’lets try this with c(2,3,4)’ print *,’ taking the result of the modulo ’ print *,’ z=1 z=2 z=3 z=4 ’ print *,’ 1 3 0 || 2 4 1 || 3 0 2 || 4 1 3 |’ print *,’ 2 4 1 || 3 0 2 || 4 1 3 || 0 2 4 |’ print *,’ ’ print *,’ would result in the mask .. ’ print *,’ F F T || F F F || F T F || F F F |’ print *,’ F F F || F T F || F F F || T F F |’ print *,’ ’ print *,’ the total number of .true.values is’ print ints, count(modulo(c,5).eq.0) call printi(’counting up along a row and removing rows’,& count(modulo(c,5).eq.0,dim=1)) call printi(’counting up along a column and removing columns’,& count(modulo(c,5).eq.0,dim=2)) call printi(’counting up along a depth and removing depths’,& count(modulo(c,5).eq.0,dim=3)) ! contains ! ! CONVENIENCE ROUTINE FOR PRINTING SMALL INTEGER MATRICES subroutine printi(title,arr) implicit none ! !@(#) print small 2d integer arrays in row-column format ! character(len=*),parameter :: all=’(*(g0,1x))’ ! a handy format character(len=*),intent(in) :: title integer,intent(in) :: arr(:,:) integer :: i character(len=:),allocatable :: biggest ! print all print all, trim(title),’:(’,shape(arr),’)’ ! print title biggest=’ ’ ! make buffer to write integer into ! find how many characters to use for integers write(biggest,’(i0)’)ceiling(log10(max(1.0,real(maxval(abs(arr))))))+2 ! use this format to write a row biggest=’(" > [",*(i’//trim(biggest)//’:,","))’ ! print one row of array at a time do i=1,size(arr,dim=1) write(*,fmt=biggest,advance=’no’)arr(i,:) write(*,’(" ]")’) enddo ! end subroutine printi end program demo_count
> the numeric arrays we will compare > 1 3 5 > 2 4 6 > > 0 3 5 > 7 4 8 > count a few basic things creating a mask from an expression > count a>b 1 > count b<a 2 > count b==a 3 > check sum = T > make a mask identifying unequal elements ... > the mask generated from a.ne.b > T F F > T F T > count total and along rows and columns ... > number of elements not equal > (ie. total true elements in the mask) > 3 > count of elements not equal in each column > (ie. total true elements in each column) > 2 0 1 > count of elements not equal in each row > (ie. total true elements in each row) > 1 2 > lets try this with c(2,3,4) > taking the result of the modulo > z=1 z=2 z=3 z=4 > 1 3 0 || 2 4 1 || 3 0 2 || 4 1 3 | > 2 4 1 || 3 0 2 || 4 1 3 || 0 2 4 | > > would result in the mask .. > F F T || F F F || F T F || F F F | > F F F || F T F || F F F || T F F | > > the total number of .true.values is > 4 > > counting up along a row and removing rows :( 3 4 ) > > [ 0, 0, 0, 1 ] > > [ 0, 1, 1, 0 ] > > [ 1, 0, 0, 0 ] > > counting up along a column and removing columns :( 2 4 ) > > [ 1, 0, 1, 0 ] > > [ 0, 1, 0, 1 ] > > counting up along a depth and removing depths :( 2 3 ) > > [ 0, 1, 1 ] > > [ 1, 1, 0 ]
STANDARD
Fortran 95 , with KIND argument - Fortran 2003
SEE ALSO
ANY(3), ALL(3), SUM(3),
fortran-lang intrinsic descriptions (license: MIT) @urbanjost
| Nemo Release 3.1 | count (3fortran) | April 28, 2024 |
