{"id":11042,"date":"2019-10-04T09:00:46","date_gmt":"2019-10-04T13:00:46","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=11042"},"modified":"2019-10-02T16:01:30","modified_gmt":"2019-10-02T20:01:30","slug":"leaf-pile","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2019\/10\/04\/leaf-pile\/","title":{"rendered":"Leaf Pile!"},"content":{"rendered":"
\n <\/p>\n

Sean<\/a>‘s pick this week is leafpile<\/tt><\/a> by Nathaniel Barlow<\/a>.\n <\/p>\n

<\/introduction><\/p>\n

As we’re finally<\/i> starting to see cooler temperatures in New England, the leaves are starting to turn. This fun submission allows MATLAB to make a pile of leaves for you to rake or have your virtual dog play in.\n <\/p>\n

To play with this, I’m going to make a simple one line live script with controls to make it so I can play with the settings. I’ll then hide the code so we can just play with the controls and make leaf piles.\n <\/p>\n

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Now let’s do a quick code review of the input parsing step that is used in leafpile<\/tt>. This is the relevant part:\n <\/p>\n

function<\/span> leafpile(N,type)\r\n%leafpile(leaves,type) makes a random pile of N leaves<\/span>\r\n% of type 'oak' or 'maple'.  N. Barlow 9\/28\/19<\/span>\r\n%leafpile(N) makes a mixed pile of N leves.<\/span>\r\n%leafpile makes a pile of 70 mixed leaves.<\/span>\r\n%The mathematical functions describing the leaf shapes were created by Hamid Naderi<\/span>\r\n%Yeganeh and given at https:\/\/blogs.scientificamerican.com\/guest-blog\/how-to-draw-with-math\/<\/span>\r\n\r\nif<\/span> nargin==0,N=70; type='mixed'<\/span>; end<\/span>;\r\nif<\/span> nargin==1, type='mixed'<\/span>; end<\/span>;\r\n\r\n⋮<\/span><\/pre>\n
function<\/span> leafpile(N,type)\r\n⋮<\/span>\r\n\r\narguments<\/span>\r\n    N(1,1) double {mustBeInteger, mustBePositive} = 70;\r\n    type {mustBeMember(type, {'mixed', 'maple', 'oak'})} = 'mixed'<\/span>;\r\nend<\/span>\r\n\r\n⋮<\/span><\/pre>\n
Now what makes arguments<\/span> better?  Well, in theory the parsing should be easier to understand and read like an English sentence.  But there’s more – Check out the Easter Egg at 26s in the video above.  Autocomplete knew the options because they were constrained by mustBeMember<\/tt>.  Pretty cool, eh?!\n   <\/p>\n
Comments<\/a><\/h3>\n
Give it a try and let us know what you think here<\/a> or leave a comment<\/a> for Nathaniel.\n   <\/p>\n
Using the new arguments<\/span><\/a> construct that Jiro wrote about<\/a> last week (my personal favorite R2019b feature) this could be rewritten with the following which would also validate the inputs:\n   <\/p>\n