numpy.isfortran

numpy.isfortran(a)

Returns True if array is arranged in Fortran-order in memory and not C-order.

Parameters :

a : ndarray

Input array.

Examples

np.array allows to specify whether the array is written in C-contiguous order (last index varies the fastest), or FORTRAN-contiguous order in memory (first index varies the fastest).

>>> a = np.array([[1, 2, 3], [4, 5, 6]], order='C')
>>> a
array([[1, 2, 3],
       [4, 5, 6]])
>>> np.isfortran(a)
False

>>> b = np.array([[1, 2, 3], [4, 5, 6]], order='FORTRAN')
>>> b
array([[1, 2, 3],
       [4, 5, 6]])
>>> np.isfortran(b)
True

The transpose of a C-ordered array is a FORTRAN-ordered array.

>>> a = np.array([[1, 2, 3], [4, 5, 6]], order='C')
>>> a
array([[1, 2, 3],
       [4, 5, 6]])
>>> np.isfortran(a)
False
>>> b = a.T
>>> b
array([[1, 4],
       [2, 5],
       [3, 6]])
>>> np.isfortran(b)
True

C-ordered arrays evaluate as False even if they are also FORTRAN-ordered.

>>> np.isfortran(np.array([1, 2], order='FORTRAN'))
False