Average a section of a column in a table based on another column values

Question

Gabi 2022-4-19

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https://ww2.mathworks.cn/matlabcentral/answers/1699695-average-a-section-of-a-column-in-a-table-based-on-another-column-values

编辑： Gabi 2024-4-17，14:11

matlab.mat

Hi,

I'm trying to average the values of a column(T3.value) coresponding to a different column in the same table (T3.index). T3.index goes form 0 to 10 in this example and output in another table with a single value for index and a single value for 'value'.

index average_value

0 x

1 y

. .

10 z

i=T3.index
for i=1:max(i)
  A(i)=mean(T3.value(i))
end

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Answer 1

KSSV 2022-4-19

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https://ww2.mathworks.cn/matlabcentral/answers/1699695-average-a-section-of-a-column-in-a-table-based-on-another-column-values#answer_945785

编辑：KSSV 2022-4-19

[c,ia,ib] = unique(T3.index) ;
N = length(c) ;
iwant = zeros(N,1) ;
for i = 1:N
    iwant(i) = mean(T3.value(ib==i)) ;
end

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Gabi 2022-4-19

Works like a charm, thank you.

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Answer 2

Lola Davidson 2022-5-19

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https://ww2.mathworks.cn/matlabcentral/answers/1699695-average-a-section-of-a-column-in-a-table-based-on-another-column-values#answer_967375

Hi Gabi,

We actually have several functions that can help with these "grouped calculations". In particular, I think groupsummary would be the easiest thing to use here:

T_means = groupsummary(T3,'index','mean');