Popular recipes by James Mills

Sending Email in Python (Python)

2013-02-24T13:47:01-08:00

Python recipe 578472 by James Mills (email, email_sending, sendmail, smtp).

Every Python Application needs to send email at some point. Whether it's for reporting errors, status updates or simply the core functionality of the system this little recipe should help! Documented and Tested.

System Authentication against /etc/shadow or /etc/passwd (Python)

2013-03-11T12:40:10-07:00

Python recipe 578489 by James Mills (authentication, password, system).

Sometimes it's useful to perform System Authentication against a Local System using the /etc/shadow or /etc/passwd password databases. This recipe provides a simple function that does exactly that.

Password Generator (mkpasswd) (Python)

2013-07-31T23:23:02-07:00

Python recipe 578468 by James Mills (generator, mkpasswd, password, secure). Revision 3.

Since everyone is posting one of these, I thought I'd post mine. I wrote this many years ago and use it everywhere.

First Class Enums in Python (Python)

2013-03-07T13:10:29-08:00

Python recipe 578485 by James Mills (enum, immutable).

True immutable symbolic enumeration with qualified value access.

Calculating Swatch Internet Time (or Beats) (Python)

2013-02-25T11:58:05-08:00

Python recipe 578473 by James Mills (beats, internet_time, swatch).

Simple function calculating Swatch Internet Time (or no. of beats).

Formatting numbers with a state machine (implementation of a regex pattern) (Python)

2011-03-22T03:40:45-07:00

Python recipe 577618 by James Mills (formatting, regular_expressions).

I was once asked to explain how the following regular expression works which formats any integer with commas for every thousand (or group of 3 digits):

(\d)(?=(\d{3})+$)

Example:

>>> import re
>>> re.sub("(\d)(?=(\d{3})+$)", "\\1,", "1234")
'1,234'

So here is an implementation of the above regular expression (as best as I could over a lunch break) that will hopefully highlight how a regular expression engine and finite automa work.

Comments and feedback welcome!

--JamesMills / prologic

Populate SQL tables from CSV data files (Python)

2011-02-02T21:21:49-08:00

Python recipe 577559 by James Mills (conversion, csv, data, python, sql).

Just a quick recipe I developed a few years ago that I thought might be useful to others. Basically it takes as input a data file with comma separated values (CSV) and translates this into a series of SQL "INSERT" statements allowing you to then feed this into MySQL, SQLite, or any other database.

Example Usage:

$ cat cars.csv Year,Make,Model,Length 1997,Ford,E350,2.34 2000,Mercury,Cougar,2.38

$ sqlite3 cars.db "CREATE TABLE cars (Year, Make, Model, Length)"

$ ./csv2sql.py cars.csv | sqlite3 cars.db

$ sqlite3 cars.db "SELECT * FROM cars" 1997|Ford|E350|2.34 2000|Mercury|Cougar|2.38

Enjoy! Feedback welcome!

cheers James Mills / prologic

Filtering CSV data by fields (cut for csv) (Python)

2011-02-02T21:39:45-08:00

Python recipe 577560 by James Mills (csv, cut, data, filter, python).

Ever wanted to take a CSV file as input, cut it up and only extract the fields that you want ?

Here's how!

$ cat cars.csv Year,Make,Model,Length 1997,Ford,E350,2.34 2000,Mercury,Cougar,2.38

$ csvcut.py -f 0 -f -1 - < cars.csv Year,Length 1997,2.34 2000,2.38

--JamesMills (prologic)

Simple Web Crawler (Python)

2011-01-31T21:57:58-08:00

Python recipe 576551 by James Mills (crawler, network, parsing, web). Revision 2.

NOTE: This recipe has been updated with suggested improvements since the last revision.

This is a simple web crawler I wrote to test websites and links. It will traverse all links found to any given depth.

See --help for usage.

I'm posting this recipe as this kind of problem has been asked on the Python Mailing List a number of times... I thought I'd share my simple little implementation based on the standard library and BeautifulSoup.

--JamesMills