Cannot use fortran code from f2py compile function

Question

I have the following Fortran code:

    !routines.f90
    module mymodule
       contains

         function add(a, b)
             real(8), intent(in):: a
             real(8), intent(in):: b
             real(8) :: add
             add = a + b
         end function
    end module

Instead of using the command: python -m numpy.f2py -m routines -c routines.f90, I want to compile from within a python script, as follows:

#main.py
import numpy as np
import numpy.f2py as f2py

with open(r'routines.f90', 'r') as f:
     source = f.read()

 f2py.compile(source, modulename='routines')

 print('OK')

But when I try to execute this script: python main.py I get the following error:

Traceback (most recent call last):
  File "main.py", line 7, in <module>
    f2py.compile(source, modulename='routines')
  File "/home/user1/anaconda3/lib/python3.6/site-packages/numpy/f2py/__init__.py", line 59, in compile
    f.write(source)
  File "/home/user1/anaconda3/lib/python3.6/tempfile.py", line 485, in func_wrapper
    return func(*args, **kwargs)
TypeError: a bytes-like object is required, not 'str'

Could you please tell me what is the issue?

ForceBru · Accepted Answer · 2019-02-03 15:11:54Z

2

open(r'routines.f90', 'r') opens your file for reading text (a.k.a. str), but, apparently, f2py.compile requires that its first argument be of type bytes. To satisfy that, open your file in binary mode:

open(r'routines.f90', 'rb')

(Also, there's no need for the first r in r'routines...', you can just do 'routines.f90', although it doesn't change much).

answered Feb 3, 2019 at 15:11

ForceBru

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2 Comments

user10957988 Over a year ago

Now I have another compilation issue with f2py which expect a fixed form fortran file, so I have start all my fortran code at 7'th column to solve that. Could you please tell me how to tell f2py use free form fortran source file? thank you

Pierre de Buyl Over a year ago

Add the argument extension='.f90' to the compile function call.

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