vectorization for nested loop where inner loop is variable depending on value of element in outer loop

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Stephanie M 2018-8-1

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https://ww2.mathworks.cn/matlabcentral/answers/413164-vectorization-for-nested-loop-where-inner-loop-is-variable-depending-on-value-of-element-in-outer-lo

评论： Stephanie M 2018-8-2

Hello,

I just learned about vectorization after trying to find a faster way to loop through all the sheets of all the files I need.

Here is basically what I'm trying to do:

for k = 1:arrayOfAllMyFilePaths
%get filepath at k
%get number of sheets in file using filepath
      for m = 1:lengthOfNumberOfSheetsInFile
      %read some data in each sheet

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OCDER 2018-8-2

编辑：OCDER 2018-8-2

Is there a requirement to vectorize this? Not everything should be vectorized or can be vectorized. Mathworks did improve their for loop speeds, and the bottleneck is probably hard drive read speed, as opposed to CPU for calculations (which is what vectorization takes advantage of). For reading files, for loop is good.

From website: https://www.mathworks.com/help/matlab/matlab_prog/vectorization.html

"MATLAB® is optimized for operations involving matrices and vectors. The process of revising loop-based, scalar-oriented code to use MATLAB matrix and vector operations is called vectorization."

Stephanie M 2018-8-2