Modifying files in python
=========================

Simple text files like ``parameters.txt``

.. literalinclude:: parameters.txt
   :linenos:

can easily be read (``"r"``) via



::

  with open("parameters.txt", "r") as prm_file:
      for line in prm_file:
          name, value = line.split("=")
          if name == "P2":
              print("[parameters.txt]  value of P2 is", float(value))
  


Other file formats like `YAML <https://pyyaml.org/wiki/PyYAMLDocumentation>`_ or
`JSON <https://docs.python.org/3/library/json.html>`_ offer a more convenient access. For example, modifying the ``parameters.yaml``

.. literalinclude:: parameters.yaml
   :linenos:

requires ``pip3 install pyyaml`` and is done by


::

  import yaml
  
  with open("parameters.yaml", "r") as prm_file:
      prm = yaml.load(prm_file, Loader=yaml.FullLoader)
  prm_E = prm["Material parameters"]["E"]
  assert prm_E["unit"] == "MPa"
  print("[parameters.yaml] value of E is", prm_E["value"])
  


Writing YAML is done via 



::

  prm_E["value"] = 17840.2
  with open("parameters_modified.yaml", "w") as prm_file:
      yaml.dump(prm, prm_file)
  

.. literalinclude:: parameters_modified.yaml
   :linenos:

  
.. include:: excel.rst
.. include:: word.rst