优化字符串的出现次数

Question

我必须计算某个字符串被包含在单元数组中的频率。问题是代码太慢了，它几乎需要1秒才能做到这一点。

    uniqueWordsSize = 6; % just a sample number
    wordsCounter = zeros(uniqueWordsSize, 1);
    uniqueWords = unique(words); % words is a cell-array

    for i = 1:uniqueWordsSize
        wordsCounter(i) = sum(strcmp(uniqueWords(i), words));
    end

我目前正在做的是将uniqueWords中的每个单词与单元格数组中的单词进行比较，并使用sum来计算strcmp返回的数组的总和。

我希望有人能帮我优化一下……对于6个单词来说，1秒实在是太多了。

编辑: ismember甚至更慢。

Answer 1

通过将unique的第三个输出与hist一起使用，可以完全删除该循环

words = {'a','b','c','a','a','c'}
[uniqueWords,~,wordOccurrenceIdx]=unique(words)
nUniqueWords = length(uniqueWords);
counts = hist(wordOccurrenceIdx,1:nUniqueWords)

uniqueWords = 
    'a'    'b'    'c'
wordOccurrenceIdx =
     1     2     3     1     1     3
counts =
     3     1     2

Answer 2

不使用显式fors的棘手方法..

clc
close all
clear all

Paragraph=lower(fileread('Temp1.txt'));

AlphabetFlag=Paragraph>=97 & Paragraph<=122;  % finding alphabets

DelimFlag=find(AlphabetFlag==0); % considering non-alphabets delimiters
WordLength=[DelimFlag(1), diff(DelimFlag)];
Paragraph(DelimFlag)=[]; % setting delimiters to white space
Words=mat2cell(Paragraph, 1, WordLength-1); % cut the paragraph into words

[SortWords, Ia, Ic]=unique(Words);  %finding unique words and their subscript

Bincounts = histc(Ic,1:size(Ia, 1));%finding their occurence
[SortBincounts, IndBincounts]=sort(Bincounts, 'descend');% finding their frequency

FreqWords=SortWords(IndBincounts); % sorting words according to their frequency
FreqWords(1)=[];SortBincounts(1)=[]; % dealing with remaining white space

Freq=SortBincounts/sum(SortBincounts)*100; % frequency percentage

%% plot
NMostCommon=20;
disp(Freq(1:NMostCommon))
pie([Freq(1:NMostCommon); 100-sum(Freq(1:NMostCommon))], [FreqWords(1:NMostCommon), {'other words'}]);