Subscripted assignment dimension mismatch ?

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MatlabFan 2013-5-21

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Hi,

I would like to fill the columns of an array of unknown number of rows with elements from a known vector; such as:

for i=1:100
vector= {bunch of calculations to find vector}
array(:,i)= vector
end

where vector is a N x 1 vector, and we obviously don't know the maximum number of rows of array. What is a computationally efficient way of doing this?

Thanks.

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Answer 1

Walter Roberson 2013-5-21

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for i = 100: -1: 1
  vector= {bunch of calculations to find vector}
  array(:,i)= vector
end

Provided, of course, that the vector is the same length for all entries.

Alternately,

i = 1;
vector= {bunch of calculations to find vector}
array = zeros(length(vector), 100);
array(:,i) = vector
for i = 2 : 100
  vector= {bunch of calculations to find vector}
  array(:,i)= vector
end

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MatlabFan 2013-5-21

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Thanks Walter. In my case, vector is not the same length for all entries. I can find, or estimate the the maximum possible length of vector. So, in this case, using what you helped me with I would write:

i = 1;
vector= {bunch of calculations to find vector}
array = zeros(Maximum_length_vector, 100);
array(:,i) = vector
for i = 2 : 100
  vector= {bunch of calculations to find vector}
  array(:,i)= vector
end

Is that the most efficient way to do it, since vector is not the same length for all entries ?

Walter Roberson 2013-5-21

编辑：Walter Roberson 2013-5-21

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If the vector length is not the same for all entries then you have a difficulty: what to do with the unoccupied locations if you are using a numeric array?

Urrr... where you wrote {bunch of calculations to find vector} was that intended to indicate creating a cell array?

Anyhow...

array = cell(100,1);
for i=1:100
  vector= ... %bunch of calculations to find vector in numeric form
  array{i} = vector;
end

This creates a cell array in which each entry is the proper length

or

array = NaN(Maximum_length_vector, 100);
for i=1:100
  vector= ... %bunch of calculations to find vector in numeric form
  array(1:length(vector),i) = vector;
end

This would leave NaN in the unused positions of a numeric array

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