If you're writing a complicated piece of code / awkward algorithm, it's a good idea to put it into a separate function. That way, it can be debugged and tested on its own, it can re-used in other code later on, and it can be hidden away from other users - and indeed from you (the author) unless you need to revisit it.
On our
Python courses, one of the exercises we set is to ask delegates to take a list of month lengths:
mlen = [31,29,31,30,31,30,31,31,30,31,30,31]
and produce two lists - one with 31 x the number 1, then 29 x the number 2 and so on, so that they have an ability to look up (for example) that day 70 of the year is in month three. The second list to contain 1 to 31, the 1 to 29, and so on - so they can also quickly look up which day of the month that day 70 of the year is.
It turns out the the algorithm also works for other things - for example converting working days of the year into week and day number (taking public holidays into account for short weeks, for example!).
Full solution to the original problem - extended beyond what I ask delegates to do in oder to allow code reuse -
[here] and an example of that re-use
[here] (written 2016-11-04)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
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[105] Distance Learning - (2004-10-31)
[294] Python generator functions, lambdas, and iterators - (2005-04-28)
[303] Lambdas in Python - (2005-05-06)
[308] Call by name v call by value - (2005-05-11)
[340] Code and code maintainance efficiency - (2005-06-08)
[386] What is a callback? - (2005-07-22)
[418] Difference between import and from in Python - (2005-08-18)
[561] Python's Generator functions - (2006-01-11)
[668] Python - block insets help with documentation - (2006-04-04)
[745] Python modules. The distribution, The Cheese Shop and the Vaults of Parnassus. - (2006-06-05)
[749] Cottage industry or production line data handling methods - (2006-06-07)
[775] Do not duplicate your code - (2006-06-23)
[821] Dynamic functions and names - Python - (2006-08-03)
[900] Python - function v method - (2006-10-20)
[912] Recursion in Python - (2006-11-02)
[913] Python - A list of methods - (2006-11-03)
[949] Sludge off the mountain, and Python and PHP - (2006-11-27)
[959] It's the 1st, not the 1nd 1rd or 1th. - (2006-12-01)
[1134] Function / method parameters with * and ** in Python - (2007-04-04)
[1163] A better alternative to cutting and pasting code - (2007-04-26)
[1202] Returning multiple values from a function (Perl, PHP, Python) - (2007-05-24)
[1464] Python Script - easy examples of lots of basics - (2007-12-08)
[1784] Global - Tcl, PHP, Python - (2008-09-03)
[1790] Sharing variables with functions, but keeping them local too - Python - (2008-09-09)
[1869] Anonymous functions (lambdas) and map in Python - (2008-11-04)
[1870] What to do with a huge crop of apples - (2008-11-04)
[1871] Optional and named parameters in Python - (2008-11-05)
[1879] Dynamic code - Python - (2008-11-11)
[2011] Conversion of OSI grid references to Eastings and Northings - (2009-01-28)
[2439] Multiple returns from a function in Python - (2009-10-06)
[2440] Optional parameters to Python functions - (2009-10-07)
[2481] Sample code with errors in it on our web site - (2009-10-29)
[2506] Good example of recursion in Python - analyse an RSS feed - (2009-11-18)
[2520] Global and Enable - two misused words! - (2009-11-30)
[2718] Python - access to variables in the outer scope - (2010-04-12)
[2766] Optional and named parameters to Python functions/methods - (2010-05-15)
[2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
[2929] Passing a variable number of parameters in to a function / method - (2010-08-20)
[2994] Python - some common questions answered in code examples - (2010-10-10)
[2998] Using an exception to initialise a static variable in a Python function / method - (2010-10-13)
[3159] Returning multiple values from a function call in various languages - a comparison - (2011-02-06)
[3280] Passing parameters to Python functions - the options you have - (2011-05-07)
[3459] Catching the fishes first? - (2011-09-27)
[3464] Passing optional and named parameters to python methods - (2011-10-04)
[3472] Static variables in functions - and better ways using objects - (2011-10-10)
[3474] Python Packages - groupings of modules. An introduction - (2011-10-11)
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[3695] Functions are first class variables in Lua and Python - (2012-04-13)
[3766] Python timing - when to use a list, and when to use a generator - (2012-06-16)
[3852] Static variables in Python? - (2012-08-29)
[3885] Default local - a good choice by the author of Python - (2012-10-08)
[3931] Optional positional and named parameters in Python - (2012-11-23)
[3945] vargs in Python - how to call a method with unknown number of parameters - (2012-12-06)
[4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
[4161] Python varables - checking existance, and call by name or by value? - (2013-08-27)
[4212] Python functions - an introduction to how they work - (2013-11-16)
[4361] Multiple yields and no loops in a Python generator? - (2014-12-22)
[4407] Python - even named code blocks are objects - (2015-01-28)
[4410] A good example of recursion - a real use in Python - (2015-02-01)
[4441] Reading command line parameters in Python - (2015-02-23)
[4448] What is the difference between a function and a method? - (2015-03-04)
[4645] What are callbacks? Why use them? An example in Python - (2016-02-11)
[4662] Recursion in Python - the classic example - (2016-03-07)
[4719] Nesting decorators - (2016-11-02)
[4724] From and Import in Python - where is the module loaded from? - (2016-11-06)
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[657] The ternary operator in Python - (2006-03-25)
[899] Python - extend v append on a list - (2006-10-20)
[955] Python collections - mutable and imutable - (2006-11-29)
[1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
[1641] Tektronix 4010 series / Python Tuples - (2008-05-13)
[1789] Looking for a value in a list - Python - (2008-09-08)
[2280] Creating and iterating through Python lists - (2009-07-12)
[2284] Strings as collections in Python - (2009-07-12)
[2368] Python - fresh examples of all the fundamentals - (2009-08-20)
[2719] Traffic lights in Python - (2010-04-13)
[2996] Copying - duplicating data, or just adding a name? Perl and Python compared - (2010-10-12)
[3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
[3181] Beware - a=a+b and a+=b are different - Python - (2011-02-23)
[3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23)
[3348] List slices in Python - 2 and 3 values forms, with an uplifting example - (2011-07-06)
[3669] Stepping through a list (or an array) in reverse order - (2012-03-23)
[3763] Spike solutions and refactoring - a Python example - (2012-06-13)
[4027] Collections in Python - list tuple dict and string. - (2013-03-04)
[4368] Shuffling a list - Ruby and Python - (2014-12-28)
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