How to sum the second position data in an array (50000x2) with the same value in the first position

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Borja Zamarreño
Borja Zamarreño 2020-6-3
编辑： Borja Zamarreño 2020-6-10
Hello everyone im having some issues trying to solve this. I have an array with this form
A=
2.79314 0.007
2.79314 0.083
2.79314 0.051
2.91205 0.06
2.91205 0.06
2.97143 0.08
2.97143 0.06
2.97143 0.07
2.97143 0.08
What i want is that whenever the data of the first column is the same, sum the data in the second column.This is what I want to obtain:
B=
2.79314 (0.007+0.083+0.051)
2.91205 (0.06+0.06+0.08)
2.97143 (0.08+0.06+0.07+0.08)
Thnak you very much in advance.
Regards.

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采纳的回答

Stephen23
Stephen23 2020-6-3
编辑：Stephen23 2020-6-3
Method one: accumarray:
>> [U,~,G] = uniquetol(A(:,1));
>> S = accumarray(G(:),A(:,2));
>> M = [U,S]
M =
2.79314 0.14100
2.91205 0.12000
2.97143 0.29000
Mehod two: splitapply:
>> S = splitapply(@sum,A(:,2),G);
>> M = [U,S]
M =
2.7931 0.1410
2.9120 0.1200
2.9714 0.2900

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