Strcmp用于MATLAB中长度不等的单元格数组 [英] Strcmp for cell arrays of unequal length in MATLAB

问题描述

有没有一种简单的方法可以在较大的字符串中找到较小的字符串单元格数组?我有两个列表，一个包含唯一元素，一个包含重复元素.我想找到较大数组中较小数组的特定模式的全部出现.我知道strcmp会比较两个单元格数组，但前提是它们的长度相等.我的第一个想法是使用循环逐步遍历更大数组的子集，但是必须有一个更好的解决方案.

Is there an easy way to find a smaller cell array of strings within a larger one? I've got two lists, one with unique elements, and one with repeating elements. I want to find whole occurrences of the specific pattern of the smaller array within the larger. I'm aware that strcmp will compare two cell arrays, but only if they're equal in length. My first thought was to step through subsets of the larger array using a loop, but there's got to be a better solution.

例如，在下面:

smallcellarray={'string1',...
                'string2',...
                'string3'};
largecellarray={'string1',...
                'string2',...
                'string3',...
                'string1',...
                'string2',...
                'string1',...
                'string2',...
                'string3'};

index=myfunction(largecellarray,smallcellarray)

会返回

index=[1 1 1 0 0 1 1 1]

推荐答案

您实际上可以使用功能

You could actually use the function ISMEMBER to get an index vector for where the cells in largecellarray occur in the smaller array smallcellarray, then use the function STRFIND (which works for both strings and numeric arrays) to find the starting indices of the smaller array within the larger:

>> nSmall = numel(smallcellarray);
>> [~, matchIndex] = ismember(largecellarray,...  %# Find the index of the 
                                smallcellarray);    %#   smallcellarray entry
                                                    %#   that each entry of
                                                    %#   largecellarray matches
>> startIndices = strfind(matchIndex,1:nSmall)  %# Starting indices where the
                                                %#   vector [1 2 3] occurs in
startIndices =                                  %#   matchIndex

     1     6

然后是从这些起始索引构建向量index的问题.这是创建此向量的一种方法:

Then it's a matter of building the vector index from these starting indices. Here's one way you could create this vector:

>> nLarge = numel(largecellarray);
>> endIndices = startIndices+nSmall;  %# Get the indices immediately after
                                      %#   where the vector [1 2 3] ends
>> index = zeros(1,nLarge);           %# Initialize index to zero
>> index(startIndices) = 1;           %# Mark the start index with a 1
>> index(endIndices) = -1;            %# Mark one index after the end with a -1
>> index = cumsum(index(1:nLarge))    %# Take the cumulative sum, removing any
                                      %#   extra entry in index that may occur
index =

     1     1     1     0     0     1     1     1

使用函数 BSXFUN 的另一种创建方式a>由 Amro 给出.创建它的另一种方法是:

Another way to create it using the function BSXFUN is given by Amro. Yet another way to create it is:

index = cumsum([startIndices; ones(nSmall-1,numel(startIndices))]);
index = ismember(1:numel(largecellarray),index);

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