如何处理 MATLAB 中函数参数的名称/值对 [英] How to deal with name/value pairs of function arguments in MATLAB

问题描述

我有一个将可选参数作为名称/值对的函数.

I have a function that takes optional arguments as name/value pairs.

function example(varargin)
% Lots of set up stuff
vargs = varargin;
nargs = length(vargs);
names = vargs(1:2:nargs);
values = vargs(2:2:nargs);

validnames = {'foo', 'bar', 'baz'};    
for name = names
   validatestring(name{:}, validnames);
end

% Do something ...
foo = strmatch('foo', names);
disp(values(foo))
end

example('foo', 1:10, 'bar', 'qwerty')

似乎在提取适当的值方面需要付出很多努力(而且它仍然不是特别健壮的再次错误指定的输入).有没有更好的方法来处理这些名称/值对?MATLAB 是否有任何辅助函数可以提供帮助?

It seems that there is a lot of effort involved in extracting the appropriate values (and it still isn't particularly robust again badly specified inputs). Is there a better way of handling these name/value pairs? Are there any helper functions that come with MATLAB to assist?

推荐答案

我更喜欢使用结构作为我的选项.这为您提供了一种存储选项的简单方法和一种定义它们的简单方法.此外，整个事情变得相当紧凑.

I prefer using structures for my options. This gives you an easy way to store the options and an easy way to define them. Also, the whole thing becomes rather compact.

function example(varargin)

%# define defaults at the beginning of the code so that you do not need to
%# scroll way down in case you want to change something or if the help is
%# incomplete
options = struct('firstparameter',1,'secondparameter',magic(3));

%# read the acceptable names
optionNames = fieldnames(options);

%# count arguments
nArgs = length(varargin);
if round(nArgs/2)~=nArgs/2
   error('EXAMPLE needs propertyName/propertyValue pairs')
end

for pair = reshape(varargin,2,[]) %# pair is {propName;propValue}
   inpName = lower(pair{1}); %# make case insensitive

   if any(strcmp(inpName,optionNames))
      %# overwrite options. If you want you can test for the right class here
      %# Also, if you find out that there is an option you keep getting wrong,
      %# you can use "if strcmp(inpName,'problemOption'),testMore,end"-statements
      options.(inpName) = pair{2};
   else
      error('%s is not a recognized parameter name',inpName)
   end
end

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