Popular recipes tagged "meta:min_python_2=6"

Equally-spaced numbers (linspace) (Python)

2015-01-12T22:16:37-08:00

Python recipe 579000 by Andrew Barnert (float, linspace, range, spread).

An equivalent of numpy.linspace, but as a pure-Python lazy sequence.

Like NumPy's linspace, but unlike the spread and frange recipes listed here, the num argument specifies the number of values, not the number of intervals, and the range is closed, not half-open.

Although this is primarily designed for floats, it will work for Fraction, Decimal, NumPy arrays (although this would be silly) and even datetime values.

This recipe can also serve as an example for creating lazy sequences.

See the discussion below for caveats.

Guard against an exception in the wrong place (Python)

2017-06-25T17:17:43-07:00

Python recipe 580808 by Steven D'Aprano (context, exception, guard, manager). Revision 2.

Sometimes exception handling can obscure bugs unless you guard against a particular exception occurring in a certain place. One example is that accidentally raising StopIteration inside a generator will halt the generator instead of displaying a traceback. That was solved by PEP 479, which automatically has such StopIteration exceptions change to RuntimeError. See the discussion below for further examples.

Here is a class which can be used as either a decorator or context manager for guarding against the given exceptions. It takes an exception (or a tuple of exceptions) as argument, and if the wrapped code raises that exception, it is re-raised as another exception type (by default RuntimeError).

For example:

try:
    with exception_guard(ZeroDivisionError):
        1/0  # raises ZeroDivisionError
except RuntimeError:
    print ('ZeroDivisionError replaced by RuntimeError')


@exception_guard(KeyError)
def demo():
    return {}['key']  # raises KeyError

try:
    demo()
except RuntimeError:
    print ('KeyError replaced by RuntimeError')

Lines Of Code (LOC) (Python)

2016-10-25T17:53:01-07:00

Python recipe 580709 by Jean Brouwers (count, lines, python2, python3, source). Revision 3.

Count the number of lines (code, comment, blank) in one or several Python source files.

Retry Decorator in Python (Python)

2017-01-11T10:10:30-08:00

Python recipe 580745 by Alfe (aspect, except, exception, retry, try).

This is a Python decorator which helps implementing an aspect oriented implementation of a retrying of certain steps which might fail sometimes. A typical example for this would be communication processes with the outside world, e. g. HTTP requests, allocation of some resource, etc. To use it, refactor the step in question into a (local) function and decorate this with the retry decorator. See examples in the discussion sector below.

Python add/set attributes to list (Python)

2015-09-29T16:28:46-07:00

Python recipe 579103 by webby1111 (attributes, class, dictionary, list, subclass). Revision 3.

Python Attribute List

Add/set attributes to python lists.

A google search for "add attributes to python lists" yields no good stackoverflow answer, hence the need for this.

Useful for machine learning stuff where you need labeled feature vectors.

This technique can be easily adapted for other built-ins (e.g. int).

The Problem

a = [1, 2, 4, 8]
a.x = "Hey!" # AttributeError: 'list' object has no attribute 'x'

The Solution

a = L(1, 2, 4, 8)
a.x = "Hey!"
print a       # [1, 2, 4, 8]
print a.x     # "Hey!"
print len(a)  # 4

# You can also do these:
a = L( 1, 2, 4, 8 , x="Hey!" )                 # [1, 2, 4, 8]
a = L( 1, 2, 4, 8 )( x="Hey!" )                # [1, 2, 4, 8]
a = L( [1, 2, 4, 8] , x="Hey!" )               # [1, 2, 4, 8]
a = L( {1, 2, 4, 8} , x="Hey!" )               # [1, 2, 4, 8]
a = L( [2 ** b for b in range(4)] , x="Hey!" ) # [1, 2, 4, 8]
a = L( (2 ** b for b in range(4)) , x="Hey!" ) # [1, 2, 4, 8]
a = L( 2 ** b for b in range(4) )( x="Hey!" )  # [1, 2, 4, 8]
a = L( 2 )                                     # [2]

Fast min/max function (Python)

2011-10-22T18:40:32-07:00

Python recipe 577916 by Raymond Hettinger (minmax, sorting).

Minimizes the number of comparisons to compute the minimum and maximum of a dataset. Uses 1.5 compares for every element, improving on the more obvious solution that does 2 comparisons per element.

ctypes CDLL with automatic errno checking (Python)

2017-01-03T10:31:26-08:00

Python recipe 580741 by Oren Tirosh .

This class extends ctypes.CDLL with automatic checking of errno and automatically raises an exception when set by the function.

How to build dobble as a Mixed Integer program. (Python)

2016-04-13T11:53:21-07:00

Python recipe 580641 by alexander baker (integer, interface, mixed, program).

A simple script to replicate the cards and symbols for the dobble game.

Safely and atomically write to a file (Python)

2016-03-23T14:14:26-07:00

Python recipe 579097 by Steven D'Aprano (atomic, file, save). Revision 3.

Saving the user's data is risky. If you write to a file directly, and an error occurs during the write, you may corrupt the file and lose the user's data. One approach to prevent this is to write to a temporary file, then only when you know the file has been written successfully, over-write the original. This function returns a context manager which can make this more convenient.

Update: this now uses os.replace when available, and hopefully will work better on Windows.

vlc.py stream capture scheduler script (Python)

2015-08-19T05:00:25-07:00

Python recipe 579096 by jwhite88 (recording, stream, vlc).

Capture network streams using vlc.py on a schedule.

Python Gpa and Cgpa Calculator for Anna university : A forked python recepie (Python)

2015-07-31T02:37:19-07:00

Python recipe 579089 by Emil george james (calculator, cgpa, gpa, python). Revision 2.

Actually this python script is a forked one from activestate code by abhijeeth vaidya.A slightly edited version of the script to calculate Gpa and Cgpa for Anna university Students.

Gpa and Cgpa Calculator

Gpa is Grade point average, which is use to determine the student academic pointer based on the value of the grade he/she acquired in single semester, where as cgpa is cumlative grade point average is to calculate the total credits and total grade acquired in his/her entire academics. Here i have determined to use grade scale of two values 5.0 and 10.0, many other academics may have different grading system.For a different grades and their grade values, You can change the value in method called getGradeData.For any bug report

python EMI calculator (Python)

2015-07-29T18:20:36-07:00

Python recipe 579086 by Emil george james (calculator, emi, python).

EMI Calculator is used to calculate Equated Monthly Installment(EMI) for Home Loans/Housing Loans,Car Loans & Personal Advantages: What all this EMI Calculator does?

. The Instant calculation of Loan EMI , Total Interest Payable and Total Payments to be done. . This can be used as EMI Calculator for Banks like HDFC, ICICI, SBI, AXIS etc. . This can be also used for calculating Home loans, Personal Loan, car loans , credit card, LIC loan

How to calculate the EMI?

The well known formula for calculating EMI is:

Formula for EMI calculation

[Formula] EMI = [(p*r/12) (1+r/12)^n]/[(1+r/12)^n – 1 ] where p = principal amount(primary loan amount) r = rate of interest per year n = Total number of Years

output:

https://emilgeorgejames.wordpress.com/2015/07/29/python-emi-equated-monthly-installment-calculator/

for more python recepies visit :https://emilgeorgejames.wordpress.com/

Yet another singleton pattern in Python using class decorators (Python)

2015-08-11T19:14:45-07:00

Python recipe 579090 by David Hollman (patterns, python, singleton). Revision 8.

Another pattern for creating singleton instances of classes in Python.

OrderedSet (Python)

2015-06-25T17:33:13-07:00

Python recipe 579071 by Sander (ordered, set).

Set that remembers original insertion order.

Python AST to XML (Python)

2015-02-05T20:18:08-08:00

Python recipe 579019 by Robert Stewart (ast, xml).

Convert Python ASTs to XML files for reading in other languages.

Keyword-only arguments in Python 2.x (Python)

2015-09-22T18:16:40-07:00

Python recipe 578993 by Cara (arguments, decorator, keyword, keyword_only). Revision 10.

This is a decorator that makes some of a function's or method's arguments into keyword-only arguments. As much as it possible, it emulates the Python 3 handling of keyword-only arguments, including messages for TypeErrors. It's compatible with Python 3 so it can be used in code bases that support both versions.

Amazon SNS handler for the logging module (Python)

2014-11-06T17:32:26-08:00

Python recipe 578956 by Andrea Corbellini (aws, logging, sns). Revision 2.

This is a handler for the standard logging module that sends notifications to the Amazon Simple Notification Service.

You can use it like so:

logging.config.dictConfig({
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format': '%(levelname)s %(asctime)s %(module)s %(process)d '
                      '%(thread)d %(message)s',
        },
        'simple': {
            'format': '%(levelname)s %(message)s',
        },
    },
    'handlers': {
        'sns': {
            'level': 'INFO',
            'class': 'SNSHandler',
            'formatter': 'verbose',
            'topic_arn': 'YOUR SNS TOPIC ARN',
        },
    },
    'loggers': {
        'YOUR MODULE': {
            'handlers': ['sns'],
            'level': 'INFO',
            'propagate': True,
        },
    },
}

socket.sendfile() (Python)

2014-06-13T13:41:25-07:00

Python recipe 578889 by Giampaolo Rodolà (backport, performance, python, sendfile). Revision 2.

This is a backport of socket.sendfile() for Python 2.6 and 2.7. socket.sendfile() will be included in Python 3.5: http://bugs.python.org/issue17552

Random Password Generation (Python)

2014-08-10T15:50:40-07:00

Python recipe 578920 by Paul Wolf (generator, password, python, random, string, strong).

Generate a password (or other secure token) using a pattern language similar to regular expressions. We'll use the strgen module that enables a user to generate test data, unique ids, passwords, vouchers or other randomized data very quickly using a template language. The template language is superficially similar to regular expressions but instead of defining how to match or capture strings, it defines how to generate randomized strings.

First n primes numbers (Python)

2014-09-20T19:33:41-07:00

Python recipe 578923 by juan . Revision 6.

Using the Sieve of Eratosthenes find the first n primes numbers.