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How can I sort "YearMonth" text using Year & Month?

MyArray = ['2019APR', '2019AUG', '2019DEC', '2019FEB', '2019JAN',  
'2019JUL', '2019JUN', '2019MAR', '2019MAY', '2019NOV', '2019OCT',  
'2019SEP', '2020APR', '2020AUG', '2020DEC', '2020FEB', '2020JAN',  
'2020JUL', '2020JUN', '2020MAR', '2020MAY', '2020NOV', '2020OCT', '2020SEP']

Output Require

['2019JAN', '2019FEB', '2019MAR', '2019APR', '2019MAY', '2019JUN',  
'2019JUL', '2019AUG', '2019SEP', '2019OCT', '2019NOV', '2019DEC',  
'2020JAN', '2020FEB', '2020MAR', '2020APR', '2020MAY', '2020JUN',  
'2020JUL', '2020AUG', '2020SEP', '2020OCT', '2020NOV', '2020DEC']

I know Sort() will sort my array in alphabetical order but any optimal custom sort function for this?

I got Answer two Ans

JS I found myself using this way:- https://jsfiddle.net/51u9nb6c/2/

And for .NET c# I mark correct answer

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5
  • This is a good place to start: google.co.uk/search?q=jquery+sort+array Commented Oct 30, 2023 at 11:55
  • You will need a sort function that accepts a custom comparison function. This function should split the date string into its components. The year can be converted to a number and used as is. If the year of two compared dates are the same then the function should look at the month string. You can use a pre-defined map/dictionary to get the numeric values of two months and then compare them. Commented Oct 30, 2023 at 12:02
  • 3
    If you're using C# you could also parse the dates with DateTime.ParseExact("2019MAR", "yyyyMMM", System.Globalization.CultureInfo.InvariantCulture) and sort them directly without a custom comparison function. I don't know if JS supports date parsing like that. Commented Oct 30, 2023 at 12:07
  • Please choose either JavaScript or C# for an implementation. Commented Oct 30, 2023 at 12:59
  • Your JS solution looks nice but can be simplified a bit: return a[1] - b[1] || months[a[0]] - months[b[0]]; Commented Oct 30, 2023 at 14:52

2 Answers 2

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In c#, you can use the Array's Sort overload that takes an Array and a Comparison as arguments:

var arr = new[] { "2019APR", "2019AUG", "2019DEC", "2019FEB", 
                  "2019JAN", "2019JUL", "2019JUN", "2019MAR", 
                  "2019MAY", "2019NOV", "2019OCT", "2019SEP", 
                  "2020APR", "2020AUG", "2020DEC", "2020FEB", 
                  "2020JAN", "2020JUL", "2020JUN", "2020MAR", 
                  "2020MAY", "2020NOV", "2020OCT", "2020SEP" };

Array.Sort(arr, (a, b) => ConvertToDateTime(a).CompareTo(ConvertToDateTime(b)));

private DateTime ConvertToDateTime(string yyyyMMM) 
    => DateTime.ParseExact(
           yyyyMMM, 
           "yyyyMMM", 
           System.Globalization.CultureInfo.InvariantCulture);

Note: You don't have to use the ConvertToDateTime method, it's just a helper to avoid writing the exact same ParseExact call twice.

See a live demo on SharpLab (without the helper method)

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5 Comments

Would it make a difference (e.g. in high performance scenarios) if ConvertToDateTime was static? (which my VS is suggesting to do)
@Fildor I guess it could make a performance difference, but I seriously doubt that would make a true performance bottle neck. Actually, after writing this comment I went to check and found a Dev.To post claiming static methods are 6 times faster than instance methods, so if it's correct it might make a more significant difference than I thought.
Static vs instance: see this question (and probably others) (though doesn't appear to be any performance tests)
Rather than consider if ConvertToDateTime should be static/not static, if performance is a question, then you would be better off not using any DateTime functions - they are notoriously slow. This is a convenience answer rather than a performant one (not saying it will be slow, just any DateTime Parse function will be slower than a simple split + dictionary lookup) (ie handcode the parsing yourself for performance).
Edit which it appears is what your js solution does - you should add that as its own answer as jsfiddle links may get lost in the future.
1

Simple :

            string[] MyArray = {"2019APR", "2019AUG", "2019DEC", "2019FEB", "2019JAN",
                "2019JUL", "2019JUN", "2019MAR", "2019MAY", "2019NOV", "2019OCT",
                "2019SEP", "2020APR", "2020AUG", "2020DEC", "2020FEB", "2020JAN",
                "2020JUL", "2020JUN", "2020MAR", "2020MAY", "2020NOV", "2020OCT", "2020SEP" };

            string[] sortedArray = MyArray.Select(x => new { s = x, date = DateTime.ParseExact(x, "yyyyMMM", System.Globalization.CultureInfo.InvariantCulture) })
                .OrderBy(x => x.date)
                .Select(x => x.s)
                .ToArray();
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3 Comments

Note that this doesn't actually sort the array, but instead returns a new array, sorted as the OP requests. Also, you're creating a new anonymous instance for each item in the array. All in all, this isn't a very memory efficient way to solve the problem, though to be fair it is a valid solution and unless the array is very long or this sort happens a lot of times, it shouldn't be a problem.
@ZoharPeled : Is you method really any different? In your solution is is not obvious what is being done under the hood.
In terms of memory usage, yes. I don't allocate any new reference types. In terms of runtime performance - I believe that if there is any difference, it's negligible.

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