ubelt 0.7.1

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Ubelt is a small library of robust, tested, documented, and simple functions
that extend the Python standard library. You've probably written and
re-written some of the functions in ubelt before (or wrote out the logic
inline). Next time, try ``pip install ubelt`` instead.

* Goal: provide simple functions that acomplish common tasks not yet addressed by the python standard library.

* Constraints: Must be low-impact pure python; it should be easy to install and use.

* Method: All functions are written with docstrings and doctests to ensure that a baseline level of documentation and testing always exists (even if functions are copy/pasted into other libraries)

* Motto: Good utilities lift all codes.


Description:
============

UBelt is cross platform and all top-level functions behave similarly on
Windows, Mac, and Linux (up to some small unavoidable differences).
Almost every function in ``ubelt`` was written with a doctest. This
provides helpful documentation and example usage as well as helping
achieve 100% test coverage (sans Python2, Windows, stuff that could not
be tested automatically, etc).

See the (Available Functions) section for detailed information.

Read the docs here: http://ubelt.readthedocs.io/en/latest/


Current Functionality
=====================
Ubelt is a currated collection of utilities.

UBelt's functionality is a mixture of the following categories:

- Timing
- Caching
- Hashing
- Command Line / Shell Interaction
- Cross-Platform Cache, Config, and Data Directories
- Symlinks
- Downloading Files
- Dictionary Histogram
- Find Duplicates
- Dictionary Manipulation
- AutoDict - Autovivification
- String-based imports
- Horizontal String Concatenation
- Standalone modules.
- `progiter <https://github.com/Erotemic/progiter>`__ for Loop Progress
- `timerit <https://github.com/Erotemic/timerit>`__ for Robust Timing and Benchmarking
- `ordered-set <https://github.com/LuminosoInsight/ordered-set>`__ for ordered set collections
- `xdoctest <https://github.com/Erotemic/xdoctest>`__ for static analysis tools


Installation:
=============

UBelt is written in pure Python and integrated into the python package
index. Just pip install it and then import it!

From pypi:
----------

::

pip install ubelt

From github:
------------

::

pip install git+https://github.com/Erotemic/ubelt.git


Purpose
=======

UBelt is a "utility belt" of commonly needed utility and helper
functions.

- Reusable code - Many functions in ``ubelt`` are simple to write
yourself (e.g. ``take``, ``memoize``, ``ensure_unicode``), but even
re-writing trivial functions takes time better spent on more
important tasks. Rewriting has its place, but not when you can just
``pip install ubelt``!

- Easy access - The entire ``ubelt`` API is exposed at the top level.
While the functions are defined in submodules, explicit imports make
easy to access any function. There are also a small number of
functions (e.g. ``ub.odict``, ``ub.ddict``, ``ub.flatten``, which are
aliases for ``collections.OrderedDict``, ``collections.DefaultDict``,
and ``itertools.chain.from_iterable``, respectively) that are
essentially aliases for functions already in Python's standard
library. I found myself using these functions so much that I wanted
easier access to them, thus they are included in ``ubelt``.

- Extra batteries - Python's standard library is "batteries included"
and provides great APIs for a variety of tasks. UBelt both extends
these batteries and provides simplified interfaces to others.

- Copy paste - It is often not desirable to add extra dependencies to
code. While I encourage installation and use of this module, I
realize that option is not always feasible. Most (but not all)
functions were also written in a way where they can be copy and
pasted into your packages own utility library without needing to add
a dependency on ``ubelt``.

History:
========

UBelt is a migration of the most useful parts of
``utool``\ (https://github.com/Erotemic/utool) into a standalone module
with minimal dependencies.

The ``utool`` library contains a number of useful utility functions, but
it also contained non-useful functions, as well as the kitchen sink. A
number of the functions were too specific or not well documented. The
``ubelt`` packages was created to is to slowly port over the most
re-usable parts of ``utool`` into a stable package.

The doctest harness in ``utool`` was ported and rewritten in a new
module called: ```xdoctest`` <https://github.com/Erotemic/xdoctest>`__,
which integrates with ``pytest`` as a plugin. All of the doctests in
``ubelt`` are run using ``xdoctest``.

A small subset of the static-analysis and code introspection tools in
``xdoctest`` are made visible through ``ubelt``.

Available Functions:
====================

Be sure to checkout the new Jupyter notebook: https://github.com/Erotemic/ubelt/blob/master/docs/notebooks/Ubelt%20Demo.ipynb

For the following functions, see corresponding doc-strings for more
details.

Some of the more interesting and useful functions and classes
implemented are:

.. code:: python

import ubelt as ub

ub.ensuredir
ub.Timerit # powerful multiline alternative to timeit
ub.Cacher # configuration based on-disk cachine
ub.cmd # combines the best of subprocess.Popen and os.system
ub.hash_data # extremely useful with Cacher to config strings
ub.repr2
ub.download
ub.AutoDict
ub.modname_to_modpath # (works via static analysis)
ub.modpath_to_modname # (works via static analysis)
ub.import_module_from_path # (Unlike importlib, this does not break pytest)
ub.import_module_from_name # (Unlike importlib, this does not break pytest)

A complete list of available functions can be seen in the
``ubelt/__init__.py`` file, which was auto-generated by
``mkinit``\ (https://github.com/Erotemic/mkinit):

.. code:: python

from ubelt.util_arg import (argflag, argval,)
from ubelt.util_cache import (CacheStamp, Cacher,)
from ubelt.util_colors import (color_text, highlight_code,)
from ubelt.util_const import (NoParam,)
from ubelt.util_cmd import (cmd,)
from ubelt.util_dict import (AutoDict, AutoOrderedDict, ddict, dict_hist,
dict_isect, dict_subset, dict_take, dict_union,
dzip, find_duplicates, group_items, invert_dict,
map_keys, map_vals, odict,)
from ubelt.util_download import (download, grabdata,)
from ubelt.util_func import (identity, inject_method,)
from ubelt.util_format import (FormatterExtensions, repr2,)
from ubelt.util_io import (delete, readfrom, touch, writeto,)
from ubelt.util_links import (symlink,)
from ubelt.util_list import (allsame, argmax, argmin, argsort, argunique,
boolmask, chunks, compress, flatten, iter_window,
iterable, peek, take, unique, unique_flags,)
from ubelt.util_hash import (hash_data, hash_file,)
from ubelt.util_import import (import_module_from_name,
import_module_from_path, modname_to_modpath,
modpath_to_modname, split_modpath,)
from ubelt.util_memoize import (memoize, memoize_method, memoize_property,)
from ubelt.util_mixins import (NiceRepr,)
from ubelt.util_path import (TempDir, augpath, compressuser, ensuredir,
expandpath, truepath, userhome,)
from ubelt.util_platform import (DARWIN, LINUX, POSIX, WIN32, editfile,
ensure_app_cache_dir, ensure_app_config_dir,
ensure_app_data_dir, ensure_app_resource_dir,
find_exe, find_path, get_app_cache_dir,
get_app_config_dir, get_app_data_dir,
get_app_resource_dir, platform_cache_dir,
platform_config_dir, platform_data_dir,
platform_resource_dir, startfile,)
from ubelt.util_str import (codeblock, ensure_unicode, hzcat, indent,)
from ubelt.util_stream import (CaptureStdout, CaptureStream, TeeStringIO,)
from ubelt.util_time import (Timer, Timerit, timestamp,)
from ubelt.orderedset import (OrderedSet, oset,)
from ubelt.progiter import (ProgIter,)


Examples
========

Here are some examples of some features inside ``ubelt``


Timing
------

Quickly time a single line.

.. code:: python

>>> import math
>>> import ubelt as ub
>>> timer = ub.Timer('Timer demo!', verbose=1)
>>> with timer:
>>> math.factorial(100000)
tic('Timer demo!')
...toc('Timer demo!')=0.1453s


Robust Timing and Benchmarking
------------------------------

Easily do robust timings on existing blocks of code by simply indenting
them. There is no need to refactor into a string representation or
convert to a single line. With ``ub.Timerit`` there is no need to resort
to the ``timeit`` module!

The quick and dirty way just requires one indent.

.. code:: python

>>> import math
>>> import ubelt as ub
>>> for _ in ub.Timerit(num=200, verbose=3):
>>> math.factorial(10000)
Timing for 200 loops
Timed for: 200 loops, best of 3
time per loop: best=2.055 ms, mean=2.145 ± 0.083 ms

Use the loop variable as a context manager for more accurate timings or
to incorporate an setup phase that is not timed. You can also access
properties of the ``ub.Timerit`` class to programmatically use results.

.. code:: python

>>> import math
>>> import ubelt as ub
>>> t1 = ub.Timerit(num=200, verbose=2)
>>> for timer in t1:
>>> setup_vars = 10000
>>> with timer:
>>> math.factorial(setup_vars)
>>> print('t1.total_time = %r' % (t1.total_time,))
Timing for 200 loops
Timed for: 200 loops, best of 3
time per loop: best=2.064 ms, mean=2.115 ± 0.05 ms
t1.total_time = 0.4427177629695507


Loop Progress
-------------

``ProgIter`` is a (mostly) drop-in alternative to
```tqdm`` <https://pypi-hypernode.com/pypi/tqdm>`__.
*The advantage of ``ProgIter`` is that it does not use any python threading*,
and therefore can be safer with code that makes heavy use of multiprocessing.

Note: ProgIter is now a standalone module: ``pip intstall progiter``)

.. code:: python

>>> import ubelt as ub
>>> def is_prime(n):
... return n >= 2 and not any(n % i == 0 for i in range(2, n))
>>> for n in ub.ProgIter(range(1000), verbose=2):
>>> # do some work
>>> is_prime(n)
0/1000... rate=0.00 Hz, eta=?, total=0:00:00, wall=14:05 EST
1/1000... rate=82241.25 Hz, eta=0:00:00, total=0:00:00, wall=14:05 EST
257/1000... rate=177204.69 Hz, eta=0:00:00, total=0:00:00, wall=14:05 EST
642/1000... rate=94099.22 Hz, eta=0:00:00, total=0:00:00, wall=14:05 EST
1000/1000... rate=71886.74 Hz, eta=0:00:00, total=0:00:00, wall=14:05 EST


Caching
-------

Cache intermediate results in a script with minimal boilerplate.

.. code:: python

>>> import ubelt as ub
>>> cfgstr = 'repr-of-params-that-uniquely-determine-the-process'
>>> cacher = ub.Cacher('test_process', cfgstr)
>>> data = cacher.tryload()
>>> if data is None:
>>> myvar1 = 'result of expensive process'
>>> myvar2 = 'another result'
>>> data = myvar1, myvar2
>>> cacher.save(data)
>>> myvar1, myvar2 = data

Hashing
-------

The ``ub.hash_data`` constructs a hash corresponding to a (mostly)
arbitrary ordered python object. A common use case for this function is
to construct the ``cfgstr`` mentioned in the example for ``ub.Cacher``.
Instead of returning a hex, string, ``ub.hash_data`` encodes the hash
digest using the 26 lowercase letters in the roman alphabet. This makes
the result easy to use as a filename suffix.

.. code:: python

>>> import ubelt as ub
>>> data = [('arg1', 5), ('lr', .01), ('augmenters', ['flip', 'translate'])]
>>> ub.hash_data(data)[0:8]
5f5fda5e

There exists an undocumented plugin architecture to extend this function
to arbitrary types. See ``ubelt/util_hash.py`` for details.

Command Line Interaction
------------------------

The builtin Python ``subprocess.Popen`` module is great, but it can be a
bit clunky at times. The ``os.system`` command is easy to use, but it
doesn't have much flexibility. The ``ub.cmd`` function aims to fix this.
It is as simple to run as ``os.system``, but it returns a dictionary
containing the return code, standard out, standard error, and the
``Popen`` object used under the hood.

.. code:: python

>>> import ubelt as ub
>>> info = ub.cmd('gcc --version')
>>> print(ub.repr2(info))
{
'command': 'gcc --version',
'err': '',
'out': 'gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609\nCopyright (C) 2015 Free Software Foundation, Inc.\nThis is free software; see the source for copying conditions. There is NO\nwarranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n',
'proc': <subprocess.Popen object at 0x7ff98b310390>,
'ret': 0,
}

Also note the use of ``ub.repr2`` to nicely format the output
dictionary.

Additionally, if you specify ``verbout=True``, ``ub.cmd`` will
simultaneously capture the standard output and display it in real time.

.. code:: python

>>> import ubelt as ub
>>> info = ub.cmd('gcc --version', verbout=True)
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

A common use case for ``ub.cmd`` is parsing version numbers of programs

.. code:: python

>>> import ubelt as ub
>>> cmake_version = ub.cmd('cmake --version')['out'].splitlines()[0].split()[-1]
>>> print('cmake_version = {!r}'.format(cmake_version))
cmake_version = 3.11.0-rc2

This allows you to easily run a command line executable as part of a
python process, see what it is doing, and then do something based on its
output, just as you would if you were interacting with the command line
itself.

Lastly, ``ub.cmd`` removes the need to think about if you need to pass a
list of args, or a string. Both will work. This utility has been tested
on both Windows and Linux.

Cross-Platform Resource and Cache Directories
---------------------------------------------

If you have an application which writes configuration or cache files,
the standard place to dump those files differs depending if you are on
Windows, Linux, or Mac. UBelt offers a unified functions for determining
what these paths are.

The ``ub.ensure_app_cache_dir`` and ``ub.ensure_app_resource_dir``
functions find the correct platform-specific location for these files
and ensures that the directories exist. (Note: replacing "ensure" with
"get" will simply return the path, but not ensure that it exists)

The resource root directory is ``~/AppData/Roaming`` on Windows,
``~/.config`` on Linux and ``~/Library/Application Support`` on Mac. The
cache root directory is ``~/AppData/Local`` on Windows, ``~/.config`` on
Linux and ``~/Library/Caches`` on Mac.

Example usage on Linux might look like this:

.. code:: python

>>> import ubelt as ub
>>> print(ub.compressuser(ub.ensure_app_cache_dir('my_app')))
~/.cache/my_app
>>> print(ub.compressuser(ub.ensure_app_resource_dir('my_app')))
~/.config/my_app

Symlinks
--------

The ``ub.symlink`` function will create a symlink similar to
``os.symlink``. The main differences are that 1) it will not error if
the symlink exists and already points to the correct location. 2) it
works\* on Windows (\*hard links and junctions are used if real symlinks
are not available)

.. code:: python

>>> import ubelt as ub
>>> dpath = ub.ensure_app_cache_dir('ubelt', 'demo_symlink')
>>> real_path = join(dpath, 'real_file.txt')
>>> link_path = join(dpath, 'link_file.txt')
>>> ub.writeto(real_path, 'foo')
>>> ub.symlink(real_path, link_path)

Downloading Files
-----------------

The function ``ub.download`` provides a simple interface to download a
URL and save its data to a file.

.. code:: python

>>> import ubelt as ub
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> fpath = ub.download(url, verbose=0)
>>> print(ub.compressuser(fpath))
~/.cache/ubelt/rqwaDag.png

The function ``ub.grabdata`` works similarly to ``ub.download``, but
whereas ``ub.download`` will always re-download the file,
``ub.grabdata`` will check if the file exists and only re-download it if
it needs to.

.. code:: python

>>> import ubelt as ub
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> fpath = ub.grabdata(url, verbose=0, hash_prefix='944389a39')
>>> print(ub.compressuser(fpath))
~/.cache/ubelt/rqwaDag.png


New in version 0.4.0: both functions now accepts the ``hash_prefix`` keyword
argument, which if specified will check that the hash of the file matches the
provided value. The ``hasher`` keyword argument can be used to change which
hashing algorithm is used (it defaults to ``"sha512"``).

Grouping
--------

Group items in a sequence into a dictionary by a second id list

.. code:: python

>>> import ubelt as ub
>>> item_list = ['ham', 'jam', 'spam', 'eggs', 'cheese', 'bannana']
>>> groupid_list = ['protein', 'fruit', 'protein', 'protein', 'dairy', 'fruit']
>>> ub.group_items(item_list, groupid_list)
{'dairy': ['cheese'], 'fruit': ['jam', 'bannana'], 'protein': ['ham', 'spam', 'eggs']}

Dictionary Histogram
--------------------

Find the frequency of items in a sequence

.. code:: python

>>> import ubelt as ub
>>> item_list = [1, 2, 39, 900, 1232, 900, 1232, 2, 2, 2, 900]
>>> ub.dict_hist(item_list)
{1232: 2, 1: 1, 2: 4, 900: 3, 39: 1}

Find Duplicates
---------------

Find all duplicate items in a list. More specifically,
``ub.find_duplicates`` searches for items that appear more than ``k``
times, and returns a mapping from each duplicate item to the positions
it appeared in.

.. code:: python

>>> import ubelt as ub
>>> items = [0, 0, 1, 2, 3, 3, 0, 12, 2, 9]
>>> ub.find_duplicates(items, k=2)
{0: [0, 1, 6], 2: [3, 8], 3: [4, 5]}

Dictionary Manipulation
-----------------------

Take a subset of a dictionary.

.. code:: python

>>> import ubelt as ub
>>> dict_ = {'K': 3, 'dcvs_clip_max': 0.2, 'p': 0.1}
>>> subdict_ = ub.dict_subset(dict_, ['K', 'dcvs_clip_max'])
>>> print(subdict_)
{'K': 3, 'dcvs_clip_max': 0.2}

Take only the values, optionally specify a default value.

.. code:: python

>>> import ubelt as ub
>>> dict_ = {1: 'a', 2: 'b', 3: 'c'}
>>> print(list(ub.dict_take(dict_, [1, 2, 3, 4, 5], default=None)))
['a', 'b', 'c', None, None]

Apply a function to each value in the dictionary (see also
``ub.map_keys``).

.. code:: python

>>> import ubelt as ub
>>> dict_ = {'a': [1, 2, 3], 'b': []}
>>> newdict = ub.map_vals(len, dict_)
>>> print(newdict)
{'a': 3, 'b': 0}

Invert the mapping defined by a dictionary. By default ``invert_dict``
assumes that all dictionary values are distinct (i.e. the mapping is
one-to-one / injective).

.. code:: python

>>> import ubelt as ub
>>> mapping = {0: 'a', 1: 'b', 2: 'c', 3: 'd'}
>>> ub.invert_dict(mapping)
{'a': 0, 'b': 1, 'c': 2, 'd': 3}

However, by specifying ``unique_vals=False`` the inverted dictionary
builds a set of keys that were associated with each value.

.. code:: python

>>> import ubelt as ub
>>> mapping = {'a': 0, 'A': 0, 'b': 1, 'c': 2, 'C': 2, 'd': 3}
>>> ub.invert_dict(mapping, unique_vals=False)
{0: {'A', 'a'}, 1: {'b'}, 2: {'C', 'c'}, 3: {'d'}}

AutoDict - Autovivification
---------------------------

While the ``collections.defaultdict`` is nice, it is sometimes more
convenient to have an infinitely nested dictionary of dictionaries.

.. code:: python

>>> import ubelt as ub
>>> auto = ub.AutoDict()
>>> print('auto = {!r}'.format(auto))
auto = {}
>>> auto[0][10][100] = None
>>> print('auto = {!r}'.format(auto))
auto = {0: {10: {100: None}}}
>>> auto[0][1] = 'hello'
>>> print('auto = {!r}'.format(auto))
auto = {0: {1: 'hello', 10: {100: None}}}

String-based imports
--------------------

Ubelt contains functions to import modules dynamically without using the
python ``import`` statement. While ``importlib`` exists, the ``ubelt``
implementation is simpler to user and does not have the disadvantage of
breaking ``pytest``.

Note ``ubelt`` simply provides an interface to this functionality, the
core implementation is in ``xdoctest`` (over as of version ``0.7.0``,
the code is statically copied into an autogenerated file such that ``ubelt``
does not actually depend on ``xdoctest`` during runtime).

.. code:: python

>>> import ubelt as ub
>>> module = ub.import_module_from_path(ub.truepath('~/code/ubelt/ubelt'))
>>> print('module = {!r}'.format(module))
module = <module 'ubelt' from '/home/joncrall/code/ubelt/ubelt/__init__.py'>
>>> module = ub.import_module_from_name('ubelt')
>>> print('module = {!r}'.format(module))
module = <module 'ubelt' from '/home/joncrall/code/ubelt/ubelt/__init__.py'>

Related to this functionality are the functions
``ub.modpath_to_modname`` and ``ub.modname_to_modpath``, which
*statically* transform (i.e. no code in the target modules is imported
or executed) between module names (e.g. ``ubelt.util_import``) and
module paths (e.g.
``~/.local/conda/envs/cenv3/lib/python3.5/site-packages/ubelt/util_import.py``).

.. code:: python

>>> import ubelt as ub
>>> modpath = ub.util_import.__file__
>>> print(ub.modpath_to_modname(modpath))
ubelt.util_import
>>> modname = ub.util_import.__name__
>>> assert ub.truepath(ub.modname_to_modpath(modname)) == modpath

Horizontal String Concatenation
-------------------------------

Sometimes its just prettier to horizontally concatenate two blocks of
text.

.. code:: python

>>> import ubelt as ub
>>> B = ub.repr2([[1, 2], [3, 4]], nl=1, cbr=True, trailsep=False)
>>> C = ub.repr2([[5, 6], [7, 8]], nl=1, cbr=True, trailsep=False)
>>> print(ub.hzcat(['A = ', B, ' * ', C]))
A = [[1, 2], * [[5, 6],
[3, 4]] [7, 8]]

Standalone tools.
-----------------

Some of the tools in ``ubelt`` have been / are being ported to
standalone modules. These tools will remain exposed in ``ubelt``, so you
have all the extra batteries at your disposal, but they will eventually
just be added as simple dependencies and the source code will be removed
from ``ubelt``.

Here are the repos containing the standalone class utilities:

- ProgIter - https://github.com/Erotemic/progiter
- Timerit - https://github.com/Erotemic/timerit
- OrderedSet - https://github.com/LuminosoInsight/ordered-set


Notes.
-----------------
Ubelt will support Python2 for the forseeable future (at least until everyone I
work with is off it followed by a probation period).

PRs are welcome. If you have a utility function that you think is useful then
write a PR. I'm likely to respond promptly.

Also check out my other projects (many of which are powered by ubelt):

- ProgIter https://github.com/Erotemic/netharn
- mkinit https://github.com/Erotemic/mkinit
- ibeis https://github.com/Erotemic/ibeis
- graphid https://github.com/Erotemic/graphid
- xdoctest https://github.com/Erotemic/xdoctest
- xinspect https://github.com/Erotemic/xinspect
- xdev https://github.com/Erotemic/xdev
- vimtk https://github.com/Erotemic/vimtk
- futures_actors https://github.com/Erotemic/futures_actors


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