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12 October 2015

Output a log message every x% of a long computation
import logging

logging.basicConfig(level=logging.INFO)


def time_to_log(data, percent=10):
    percent = percent if percent > 1 else percent * 100
    data_size = len(data)
    log_every = data_size * percent / 100
    return float(data_size), lambda i: not i % log_every


data = range(100)
data_size, is_time_to_log = time_to_log(data, 0.2)

for i, d in enumerate(data):
    if is_time_to_log(i):
        logging.info("processing... {:.2%}".format(i / data_size))
    pass  # do whatever is needed
logging.info("processing... 100.00%")

10 October 2015

another reader's digest

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSWDdsxk6ho-2FMay5rVbvceNMNg55I6KZazOsPlvbG2-hmbEv2Og
The borg pattern


http://images.fineartamerica.com/images-medium-large/2-neural-network-pasieka.jpg
Neural network, 11 LOC

http://farm2.static.flickr.com/1303/1368498596_b9abff25bb.jpg
Best practices
to manage a Python code library


http://www.funbrain.com/guess/magic.gif
0x5f3759df
Another magic number

comprendo comprehension ?

 Youtube File System
 

http://static5.businessinsider.com/image/4e7f557369beddb21d00003b-480/crystal-ball-fortune-teller.jpg
A peek in the future

Print
>>> print

>>> from __future__ import print_function
>>> print
<built-in function print>

division
>>> 3/2
1
>>> from __future__ import division
>>> 3/2
1.5

Hold your brace
>>> from __future__ import braces
SyntaxError: not a chance (<input>, line 1)


21 September 2015

30 000 % speed improvement

What’s a bug ?

Compile ?

String formatting


Cutting off the internet

True or False ?

Here are different way to transform values from a config file to a boolean
Which is your favourite ?

devpi install z3c.appconfig

>>> from z3c.appconfig.utils import asBool
>>> asBool("true")
True
>>> asBool(1)
True
>>> asBool(-1)
True
>>> asBool("no")
False
>>> asBool("yes")
True
>>> asBool("Yes")
True
>>> asBool("YES")
True
>>> asBool("NO")
False
>>> asBool("off")
False
>>> asBool("on")
True
>>> asBool('Lorem')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nlaurance/PycharmProjects/dev_venv/local/lib/python2.7/site-packages/z3c/appconfig/utils.py", line 18, in asBool
    raise ValueError("Invalid boolean: %s" % value)
ValueError: Invalid boolean: lorem
>>> asBool(456)
True
>>> asBool(0)
False

devpi install distutils

>>> from distutils.util import strtobool
>>> strtobool('true')
1
>>> strtobool('False')
0
>>> strtobool('off')
0
>>> strtobool('on')
1
>>> strtobool('y')
1
>>> strtobool('n')
0
>>> strtobool('lorem')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/distutils/util.py", line 325, in strtobool
    raise ValueError, "invalid truth value %r" % (val,)
ValueError: invalid truth value 'lorem'
>>> strtobool('1')
1
>>> strtobool(456)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/distutils/util.py", line 319, in strtobool
    val = string.lower(val)
  File "/usr/lib/python2.7/string.py", line 226, in lower
    return s.lower()
AttributeError: 'int' object has no attribute 'lower'

Roll your own

>>> def asbool(value):
...     return str(value).lower() in ('true', 't', 'on', 'yes', 'y', '1', '1.0')
...
>>> asbool('f')
False
>>> asbool('YES')
True
>>> asbool(True)
True
>>> asbool(False)
False
>>> asbool(0)
False
>>> asbool(1)
True
>>> asbool(-1)
False
>>> asbool('On')
True

08 September 2015

Another panda sweet treat





Gesture Typing, the swipe keyboard

Retro Gaming

Sanitize the inputs



Validate your CSV



Global variables are BAD



Profiler

 


By Reference or by value ?
Last but not least, there is no such thing as passing variable by value or by reference.
They are names, take 25 minutes of attention and listen to Ned Batchelder, a name you’ll cross often

31 August 2015



Crunching the crashes
A nice tutorial for pandas, showing how to manipulate and analyse a big CSV file ( 6 000 000 rows +)


lost in data
This one is fun! Another tutorial around data analysis with python, this time working against a TV series database


 


playing or learning ? both !
Willing to learn python from the start by example on a nice slope ?
A great site
has loads of puzzles to solve in python, it starts at elementary level.
You can then publish (or not) your solution and vote for the best proposal.
Great to see others answers and learn from it.