flametree 0.1.8

Python file and zip operations made easy

.. raw:: html

<p align="center">
<img alt="DNA Cauldron Logo" title="DNA Cauldron Logo" src="https://raw.githubusercontent.com/Edinburgh-Genome-Foundry/Flametree/master/docs/logo.png" width="500">
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<h2 align="center"> Python file operations made easy </h2>

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:target: https://coveralls.io/github/Edinburgh-Genome-Foundry/Flametree


Flametree is a Python library which provides a simple syntax for handling files and folders
(no ``os.path.join``, ``os.listdir`` etc.), and works the same way for different file systems.

Write a Flametree program to read/write files in disk folders, and your code will also be
able to read/write in zip archives and virtual (in-memory) archives - which is particularly
useful on web servers.

As an illustration, here is how to use Flametree to read a file ``texts/poems/the_raven.txt``, replace all
occurences of the word "raven" by "seagull" in the text, and write the result to a new
file ``the_seagull.txt`` in the same folder:

.. code:: python

from flametree import file_tree

with file_tree("texts") as root:
poem_text = root.poems.the_raven_txt.read()
new_text = poem_text.replace("raven", "seagull")
root.poems._file("the_seagull.txt").write(new_text)

Even in this very simple use case, the syntax is clearer than the ``os`` way,
which would write as follows:

.. code:: python

import os

with open(os.path.join("poems", "the_raven.txt"), "r") as f:
poem_text = f.read()
new_text = poem_text.replace("raven", "seagull")
with open(os.path.join("poems", "the_seagull.txt"), "w") as f:
content = f.write(new_text)

Moreover, the same Flametree code also works for files inside a zip archive:

.. code:: python

with file_tree("my_archive.zip") as root:
poem_text = root.poems.the_raven_txt.read()
new_text = poem_text.replace("raven", "seagull")
root.poems._file("the_seagull.txt").write(new_text)

Now in hard mode: suppose that your server receives binary zip data of an
archive containing ``poems/the_raven.txt``, and must return back a new zip
containing a file ``poems/the_seagull.txt``. Here again, the syntax of the core
operations is the same:

.. code:: python

destination_zip = file_tree("@memory") # Create a new virtual zip
with file_tree(the_raven_zip_data) as root:
poem_text = root.poems.the_raven_txt.read()
new_text = poem_text.replace("raven", "seagull")
destination_zip._dir("poems")._file("the_seagull.txt").write(new_text)
destination_zip_data = destination_zip._close()
# Now send the data to the client

See section *Usage* below for more examples and features.

Installation
-------------

Flametree should work on Windows/Max/Linux, with Python 2 and 3, and has no external dependency.

It can be installed by unzipping the source code in one directory and using this command: ::

sudo python setup.py install

You can also install it directly from the Python Package Index with this command: ::

sudo pip install flametree


Contribute
-----------

Flametree is an open-source software originally written by Zulko_ and released on Github_
under the MIT licence (Copyright Edinburgh Genome Foundry).
Everyone is welcome to contribute !
In particular if you have ideas of new kinds of file systems to add to Flametree.


Usage
-------

Opening a file tree
~~~~~~~~~~~~~~~~~~~~

Here is how you open different kinds of file systems:

.. code:: python

from flametree import file_tree

# Open a directory from the disk's file system:
root = file_tree("my_folder/")

# Open a zip archive on the disk:
root = file_tree("my_archive.zip")

# Connect to a file-like object (file handle, StringIO...) of a zip:
root = file_tree(file_like_object)

# Create a virtual 'in-memory' zip file:
root = file_tree("@memory")

# Open some data string representing a zip to read
root = file_tree(some_big_zip_data_string)



In the two first examples, if ``my_folder`` or ``my_archive.zip`` do not exist, they
will be automatically created. If they do exist, it is possible to completely overwrite
them with the option ``replace=True``.

Exploring a file tree:
~~~~~~~~~~~~~~~~~~~~~~

Once you have created the ``root`` element with one of the methods above, you can display the whole
file tree with ``root._tree_view()`` :

.. code::

>>> print (root._tree_view())
texts/
poems/
dover_beach.txt
the_raven.txt
the_tyger.txt
todo_list.txt
figures/
figure1.png
figure2.png
Readme.md


The attributes of a directory like ``root`` are its files and subdirectories.
For instance to print the content of ``dover_beach.txt`` you would write:

.. code:: python

print( root.texts.poems.dover_beach_txt.read() )

or even simpler:

.. code:: python

root.texts.poems.dover_beach_txt.print_content()

Notice that the ``.`` before ``txt`` was replaced by ``_`` so as to form a valid
attribute name.

This syntactic sugar is particularly useful to explore a file tree in
IPython Notebooks or other editors offering auto-completion:


.. image:: https://raw.githubusercontent.com/Edinburgh-Genome-Foundry/Flametree/master/docs/autocomplete.png
:alt: [illustration]
:align: center

Alternatively, you can access files and directories using dictionary calls:

.. code:: python

root["texts"]["poems"]["dover_beach.txt"]

To iterate through the subdirectories of a directory, use the ``_dirs`` attribute:

.. code:: python

for subdirectory in root._dirs:
print (subdirectory._name) # Will print 'texts' and 'figures'

To iterate through the files of a directory, use the ``_files`` attribute:

.. code:: python

for f in root.figures._files:
print (f._name) # Will print 'figure1.png' and 'figure2.png'

Finally, use ``_all_files`` to iterate through all files nested in a directory.
The snippet below prints the content of all ``.txt`` files in the file tree:

.. code:: python

for f in root._all_files:
if f._name.endswith(".txt"):
f.print_content()

Creating files and folders
~~~~~~~~~~~~~~~~~~~~~~~~~~~

To create a new subdirectory use ``_dir``:

.. code:: python

root._dir("data") # create a 'data' folder at the root
root.data._dir("reports") # create a 'reports' folder under `root/data`

To create a new file use ``_file``:

.. code:: python

root._file("joke.txt") # create a 'joke.txt' file at the root.
root.texts._file("hello.txt") # create 'hello.txt' in `root/texts`.

To write content in a file, use ``.write``:

.. code:: python

root.joke_txt.write("A plateau is the highest form of flattery.")

Writing to a file will use mode ``a`` (append) by default. To overwrite
the file set the write mode to ``"w"``. Let's erase and rewrite that ``joke.txt``:

.. code:: python

root.joke_txt.write("'DNA' stands for National Dyslexic Association.", "w")

File and directory creation commands can be chained.
Let us create some new folders ``data/`` and ``data/test_1/``, and
write to file ``data/test_1/values.csv``, all in a single line:

.. code:: python

root._dir("data")._dir("test_1")._file("values.csv").write("1, 15, 25")

Beware that ``._dir`` and ``._file`` **overwrite their target by default**, which means that if you write:

.. code:: python

root._dir("data")._file("values_1.csv").write("1, 4, 7")
root._dir("data")._file("values_2.csv").write("2, 9, 7")

The directory ``data`` will only contain ``values_2.csv``, because the second
line's ``_dir("data")`` erases the ``data`` directory and starts a new one. To avoid this,
either use ``root.data`` in the second line:

.. code:: python

root._dir("data")._file("values_1.csv").write("1, 4, 7")
root.data._file("values_2.csv").write("2, 9, 7")

Or use ``replace=False`` in ``_dir``:

.. code:: python

root._dir("data")._file("values_1.csv").write("1, 4, 7")
root._dir("data", replace=False)._file("values_2.csv").write("2, 9, 7")


Other operations
~~~~~~~~~~~~~~~~~~

You can move, copy, and delete a file with ``.move(folder)``, ``.copy(folder)``,
``.delete()``, and a directory with ``._move(folder)``, ``._copy(folder)``,
``._delete()``.

.. code:: python

root.data.values1_csv.delete() # delete file 'values1.csv'
root.data._delete() # delete directory 'data'
# Move folder `plots` from `root/figures` to `other_root/figures`
root.figures.plots._move(other_root.figures)
# Move file `fig.png` from `root/figures` to `other_root/figures`
root.figures.fig_png.move(other_root.figures)

Special rules for ZIP archives
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It is not currently possible to modify/delete a file that is already zipped
into an archive (because zips are not really made for that, it would
be doable but would certainly be a hack).

When creating files and folders in a zip with Flametree, the changes in the actual zip
will only be performed by closing the ``root`` with ``root._close()``
(after which the ``root`` can't be used any more). If it is an in-memory zip, ``root._close()``
returns the value of the zip content as a string (Python 2) or bytes (Python 3).

Here are a few examples:

.. code:: python

root = file_tree("archive.zip")
root._file("hello.txt").write("Hi there !")
root._close()

# Equivalent to the previous, using `with`:
with file_tree("archive.zip") as root:
root._file("hello.txt").write("Hi there !")

# Getting binary data of an in-memory zip file:
root = file_tree("@memory")
root._file("hello.txt").write("Hi there !")
binary_data = root._close()


Using file writers from other libraries
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some libraries have file-generating methods which expect a file name or a file
object to write too.
You can also feed Flametree files to these functions. for instance here is
how to use Weasyprint to create a PDF ``pdfs/report.pdf``

.. code:: python

import weasyprint
from flametree import file_tree
root = file_tree(".") # or 'archive.zip' to write in an archive.
html = weasyprint.HTML(string="<b>Hello</b> world!", base_url='.')
html.write_pdf(root._dir("pdfs")._file("test.pdf"))

And here is how you would save a Matplotlib figure in a zip archive:

.. code:: python

import matplotlib.pyplot as plt
from flametree import file_tree
fig, ax = plt.subplots(1)
ax.plot([1, 2, 3], [3, 1, 2])
with file_tree("archive.zip") as root:
fig.savefig(root._dir("plots")._file("figure.png"), format="png")

That's all folks !


.. _Zulko: https://github.com/Zulko/
.. _Github: https://github.com/Edinburgh-Genome-Foundry/flametree