add internal parts of a vector

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Me
Me 2024-1-15
回答： Stephen23 2024-1-15
Dear all, I have a problem with the sum of internal parts of a vector.I'll explain my problem below.I am analyzing a series of data, after having selected the vector (vectorA) with the quantities I need, I have to add the parts in which the terms equal to 1 follow each other. Example:
vectorA=[1;1;1;1;1;3;4;8;1;1;1;2;9;1;1;1;1;4;1;1]
I have to add only the 1 values (in groups), obtaining a vectorB which has as many terms as the groups of 1:
vectorB=[5;3;4;2].
In short, I need to know how many groups of terms equal to 1 I have and their sum. I tried with if loop, but I didn't succeed.
Thanks in advance for the help!

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Dyuman Joshi
Dyuman Joshi 2024-1-15
编辑：Dyuman Joshi 2024-1-15
Ran in:
Here is a simple way of dividing the data into groups of 1 and counting the number of elements for each sub-group -
%Converted to a row vector for displaying the values in a single line
vectorA=[1;1;1;1;1;3;4;8;1;1;1;2;9;1;1;1;1;4;1;1].';
%Values equal to 1
idx = vectorA == 1
idx = 1×20 logical array
1 1 1 1 1 0 0 0 1 1 1 0 0 1 1 1 1 0 1 1
%Convert the logical vector to a char vector
vec = sprintf('%d', idx)
vec = '11111000111001111011'
%split the char vector with '0' as delimiter
vec = strsplit(vec, '0')
vec = 1×4 cell array
{'11111'} {'111'} {'1111'} {'11'}
%Get the length of each sub-string
out = cellfun('length', vec)
out = 1×4
5 3 4 2
In case the data does not start or end with 1, there will be empty sub-strings present after splitting, as the first or the last character will be a delimiter; then remove the corresponding values -
out = out(out~=0)
out = 1×4
5 3 4 2

更多回答（3 个）

Stephen23
Stephen23 2024-1-15
Ran in:
A = [1;1;1;1;1;3;4;8;1;1;1;2;9;1;1;1;1;4;1;1]
A = 20×1
1 1 1 1 1 3 4 8 1 1
X = A==1;
Y = cumsum([1;diff(X)>0]);
Z = accumarray(Y,X)
Z = 4×1
5 3 4 2
Hassaan
Hassaan 2024-1-15
Ran in:
vectorA = [1; 1; 1; 1; 1; 3; 4; 8; 1; 1; 1; 2; 9; 1; 1; 1; 1; 4; 1; 1];
vectorB = sum_consecutive_ones(vectorA);
disp(vectorB)
5 3 4 2
function vectorB = sum_consecutive_ones(vectorA)
% Ensure vectorA is a column vector
vectorA = vectorA(:);
% Initialize the count and the result vector
count = 0;
vectorB = [];
% Loop over the elements of vectorA
for i = 1:length(vectorA)
if vectorA(i) == 1
count = count + 1; % Increment count if the current element is 1
elseif count > 0
vectorB(end + 1, 1) = count; % Add the count to vectorB if the sequence ends
count = 0; % Reset the count
end
end
% If the last element of vectorA is 1, we need to add the count to vectorB
if count > 0
vectorB(end + 1, 1) = count;
end
end
---------------------------------------------------------------------------------------------------------------------------------------------------------
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Shivam
Shivam 2024-1-15
Ran in:
Hi,
From the provided information, I understand that you want to identify and sum the consecutive ones in a vector and then record the length of each sequence of consecutive ones into a new vector.
You can follow the below workaround to achieve the goal:
% Initialize vectorA with specific values
vectorA = [1; 1; 1; 1; 1; 3; 4; 8; 1; 1; 1; 2; 9; 1; 1; 1; 1; 4; 1; 1];
n = length(vectorA);
% Initialize an empty array to hold the counts of consecutive ones
vectorB = [];
% Initialize a counter for consecutive ones
countOne = 0;
for i = 1:n
if vectorA(i) == 1
countOne = countOne + 1; % Increment the counter for consecutive ones
% If the current element is not 1 and there is a non-zero count of ones
elseif countOne
% Append the count of consecutive ones and
% reset the counterOne to 0
vectorB = [vectorB countOne];
countOne = 0;
end
end
% After the loop, if there is a non-zero count of ones left
if countOne
% Append the remaining count of consecutive ones to vectorB
vectorB = [vectorB countOne];
end
disp(vectorB);
5 3 4 2
I hope it helps.
Thanks

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