Find Number of Elements in an Array

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Burak Alakus
Burak Alakus 2019-8-19
评论： Adam Danz 2024-6-5
Hello guys. I want to find the number of elements in a string array.
Lets say A = ['KM'; 'KL'; 'MN'; 'KM', 'MM', 'KL'] is my array list.
It should give output as;
[2,2,1,1] since my string array includes 2 KM, 2 KL, 1MN, and 1MM.
How can i do that?

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采纳的回答

Lola Davidson
Lola Davidson 2024-6-4
Ran in:
If you prefer avoiding cell arrays and/or tables, groupcounts (introduced in R2019a) can do this straight away
A = ['KM'; 'KL'; 'MN'; 'KM'; 'MM'; 'KL'];
groupcounts(A)
ans = 4x1
2 2 1 1
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That said, if you like the decoration, you can put it in a table before sending it to groupcounts.
A = ["KM"; "KL"; "MN"; "KM"; "MM"; "KL"];
groupcounts(table(A),1)
ans = 4x3 table
A GroupCount Percent ____ __________ _______ "KL" 2 33.333 "KM" 2 33.333 "MM" 1 16.667 "MN" 1 16.667

更多回答（3 个）

Adam Danz
Adam Danz 2019-8-19
The "A" array provided in the question will result in a dimensions mismatch error. I'm assuming A is an [nx2] char array.
A = ['KM'; 'KL'; 'MN'; 'KM'; 'MM'; 'KL'];
% Convert char array to cell array of strings
Acell = cellstr(A);
% Find groups of strings
[groups, groupID]= findgroups(Acell(:));
% Count members of each group
count = sum(groups(:).' == unique(groups(:)),2);
% Display results in a table
countTable = table(groupID(:),count(:),'VariableNames',{'Group','Count'});
Result
countTable =
4×2 table
Group Count
_____ _____
'KL' 2
'KM' 2
'MM' 1
'MN' 1
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显示 1更早的评论
Adam Danz
Adam Danz 2019-8-20
Glad I could help and learn along with ya!
Adam Danz
Adam Danz 2024-6-5
June 5, 2024 - I unaccepted this answer in favor of Lola's better solution using groupcounts that became available in R2019a. Prior to R2019a, I would recommend Steven Lord's answer.

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Andrei Bobrov
Andrei Bobrov 2019-8-19
编辑：Andrei Bobrov 2019-8-19
A = {'KM'; 'KL'; 'MN'; 'KM'; 'MM'; 'KL'};
out = varfun(@x,table(A),'GroupingVariables','A')
Steven Lord
Steven Lord 2024-6-4
Ran in:
Yet another way to do this:
A = ['KM'; 'KL'; 'MN'; 'KM'; 'MM'; 'KL'];
[counts, values] = histcounts(categorical(cellstr(A)))
counts = 1x4
2 2 1 1
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values = 1x4 cell array
{'KL'} {'KM'} {'MM'} {'MN'}

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