在具有不同类型元素的单元格数组中查找字符串 [英] Find string in cell array with elements of different types

问题描述

我有一个接受可变参数的函数.这些参数是参数值对，因此varargin是一个单元格数组，其中每个奇数索引元素都是一个字符串(参数)，但是偶数索引元素可以是字符串，数字或字符串的单元格数组.我想在varargin中找到特定字符串的索引.我有一个可行的解决方案，但是它两次使用arrayfun；有没有更清洁/更快/更有效的方式在这种单元阵列中查找字符串?生成的index将用于从varargin中删除该元素和下一个元素.我想最大程度地减少新变量的创建.

I have a function that takes variadic arguments. These arguments are parameter-value pairs, so varargin is a cell array in which every odd-indexed element is a string (the parameter), but the even-indexed elements can be a string, number, or cell array of strings. I want to find the index of a particular string in varargin. I have a working solution, but it uses arrayfun twice; is there a cleaner/faster/more effective way of find a string in such a cell array? The resulting index will be used to remove that element and the following one from varargin. I would like to minimize creation of new variables.

str_to_find = 'paramX'
finds = arrayfun(@(i) strfind(varargin{i},str_to_find), 1:length(varargin), 'UniformOutput', 0);
finds2 = arrayfun(@(i) ~iscell(finds{i}) && ~isempty(finds{i}), 1:length(finds));
index = find(finds2==1);

varargin(index)=[];
varargin(index)=[];

给出varargin为{'paramA', 'valueA', 'paramB', 9, 'paramX', {'z','x','c'}，然后finds为[] [] [] [] [1] {1x3 cell}，finds2为0 0 0 0 1 0，并且index为5.因此，我的解决方案可以满足我的需求，但这看起来很难看.我只会使用finds2(即不创建index)从varargin中删除该元素，但是我还需要删除其后的那个元素.

Given varargin is {'paramA', 'valueA', 'paramB', 9, 'paramX', {'z','x','c'}, then finds is [] [] [] [] [1] {1x3 cell}, finds2 is 0 0 0 0 1 0, and index is 5. So, my solution does what I need, but it just seems ugly. I would just use finds2 (i.e., not create index) to delete that element from varargin, but I also need to remove the one after it.

推荐答案

您可以使用内置函数strcmp，该函数应该相当快:

You can use the built-in function strcmp which should be fairly fast:

idx  = strcmp(str_to_find, varargin);

这将为您提供所有与目标匹配的字符串的单元格的索引.

and that will give you an index to all cell elements that are strings matching the target.

然后，要修剪这些元素，可以使用

Then, for pruning those elements, you can use

varargin( or(idx, [0 idx(1:end-1)]) ) = [];

假设idx是一个行数组.

assuming that idx is a row array.

最后，您可能还需要运行一些格式检查，以确保用户未按错误的顺序(或参数名称与参数名称匹配)输入参数对，否则这种代码的行为会很奇怪

Finally, you may also want to run some format checks to make sure that the user has not entered argument-pairs in the wrong order (or with an argument name that matches the parameter name) otherwise this kind of code will behave strangely.

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