Mat*_*ock 3 python fortran numpy f2py
如果我打算将一个布尔值 NumPy 数组传递给 Fortran 变量，应该如何输入它们f2py？我已经尝试了integer*1和logical*1，但是这两个都表明该数组已被复制。
例如，如果我编译文件foo.f95，包含：
subroutine foo(x, n)
logical*1 x(n)
!f2py intent(in) x
!f2py intent(hide), depend(x) :: n=shape(x,0)
...
end subroutine
使用f2py -c -m foo foo.f90 -DF2PY_REPORT_ON_ARRAY_COPY=1并运行以下内容：
import numpy as np
import foo
x = np.random.randn(100) < 0
foo.foo(x)
它打印
copied an array: size=100, elsize=1
如果我更改logical*1为integer*1. Fortran 文件中布尔数组的正确类型是什么，以便不复制数组？
请注意，这不是内存连续性的问题，因为数组是一维的——foo.foo(np.asfortranarray(x))打印相同的复制消息。
从一些实验（*），似乎是Python的/ f2py对待np.int8与兼容logical*1，同时，np.bool或np.bool8因某些原因。插入print *, "(fort) x = ", xfoo.f90 后，我们得到：
>>> foo.foo( np.array( [ True, False, False ], dtype=np.bool ) )
copied an array: size=3, elsize=1
(fort) x = T F F
>>> foo.foo( np.array( [ False, True, False ], dtype=np.bool8 ) )
copied an array: size=3, elsize=1
(fort) x = F T F
>>> foo.foo( np.array( [ False, False, True ], dtype=np.int8 ) ) # no copy
(fort) x = F F T
因为True和False只是简单地映射到 1 和 0，所以int8在 Python 端使用数组可能会很方便。
(*) 一些实验
在这里，我将 f2py 意图注释更改inout为查看是否可以从 Fortran 端修改数组。
foo.f90：
subroutine foo(x, n)
use iso_c_binding
implicit none
integer n
logical*1 x( n )
! logical x( n )
! logical(c_bool) x( n )
!f2py intent(inout) x
!f2py intent(hide), depend(x) :: n=shape(x,0)
print *, "(fort) x = ", x
print *, "(fort) sizeof(x(1)) = ", sizeof(x(1))
print *, "(fort) resetting x(:) to true"
x(:) = .true.
end subroutine
测试.py：
import numpy as np
import foo
for T in [ np.bool, np.bool8,
np.int, np.int8, np.int32, np.int64,
np.uint, np.uint8, np.uint32, np.uint64,
np.dtype('b'), np.dtype('int8'), np.dtype('int32') ]:
print( "-------------------------" )
print( "dtype =", T )
x = np.array( [ True, False, True ], dtype=T )
print( "input x =", x )
try:
foo.foo( x )
print( "output x =", x )
except:
print( "failed" )
结果与logical*1：
-------------------------
dtype = <class 'bool'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'numpy.bool_'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'int'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int8'>
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = <class 'numpy.int32'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint8'>
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = <class 'numpy.uint32'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = int8
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = int8
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = int32
input x = [1 0 1]
failed
结果logical（默认类型）：
-------------------------
dtype = <class 'bool'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'numpy.bool_'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'int'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int8'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int32'>
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 4
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = <class 'numpy.int64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint8'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint32'>
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 4
(fort) resetting x(:) to true
output x = [1 1 1]
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = int8
input x = [1 0 1]
failed
-------------------------
dtype = int8
input x = [1 0 1]
failed
-------------------------
dtype = int32
input x = [1 0 1]
(fort) x = T F T
(fort) sizeof(x(1)) = 4
(fort) resetting x(:) to true
output x = [1 1 1]
结果logical(c_bool)（通过iso_c_binding）：
-------------------------
dtype = <class 'bool'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'numpy.bool_'>
input x = [ True False True]
failed
-------------------------
dtype = <class 'int'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int8'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.int32'>
input x = [1 0 1]
(fort) x = T F F
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [65793 0 1]
-------------------------
dtype = <class 'numpy.int64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint8'>
input x = [1 0 1]
failed
-------------------------
dtype = <class 'numpy.uint32'>
input x = [1 0 1]
(fort) x = T F F
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [65793 0 1]
-------------------------
dtype = <class 'numpy.uint64'>
input x = [1 0 1]
failed
-------------------------
dtype = int8
input x = [1 0 1]
failed
-------------------------
dtype = int8
input x = [1 0 1]
failed
-------------------------
dtype = int32
input x = [1 0 1]
(fort) x = T F F
(fort) sizeof(x(1)) = 1
(fort) resetting x(:) to true
output x = [65793 0 1]
出于某种原因，这最后一个logical(c_bool)不适用于上述用法......（f2py 似乎认为logical(c_bool)是 4 个字节，而 gfortran 将其视为 1 个字节，所以有些事情是不一致的......）
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