Count frequencies of occurence using both text and number

Question

Beth Lewis 2021-8-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1413362-count-frequencies-of-occurence-using-both-text-and-number

编辑： Beth Lewis 2021-8-17

采纳的回答： Adam Danz

在 MATLAB Online 中打开

Hi there,

I'll give a brief example of my table:

Fish species:          Count:
red fish                2
red fish                4
red fish                9
blue fish               11
blue fish               2
blue fish               2
blue fish               1
yellow fish             2
yellow fish             10

etc etc...

What I am trying to do is to find the sum of all 'red fish' 'blue fish' etc with about 500 rows and do it automatically not manually.

So I want the code to finish saying this:

red fish                15
blue fish               16
yellow fish             12

for all 29 fish species...

Help?

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Answer 1

Adam Danz 2021-8-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1413362-count-frequencies-of-occurence-using-both-text-and-number#answer_768957

编辑：Adam Danz 2021-8-17

在 MATLAB Online 中打开

Use groupsummary

% Produce table
% I use categorical variables but you can you strings or char-vectors
rng('default') % for reproducibility, do no include in your implementation
cats = categorical(["red fish","blue fish"])';
fishList = cats(randi(2,500,1)); 
counts = randi(10,500,1); 
T = table(fishList, counts, 'VariableNames', {'Fish','Counts'}); 
% Show first few rows of table
head(T)
ans = 8×2 table
      Fish       Counts
    _________    ______

    blue fish       6  
    blue fish       6  
    red fish        9  
    blue fish       3  
    blue fish       4  
    red fish        2  
    red fish       10  
    blue fish       7  
% Count each fish group
groupsummary(T,'Fish')
ans = 2×2 table
      Fish       GroupCount
    _________    __________

    blue fish       243    
    red fish        257    