How to find the maximum index in a struct

Question

EK 2021-4-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/810650-how-to-find-the-maximum-index-in-a-struct

评论： Stephen23 2021-4-23

I need to read in an unknown number of data files from the current working directory. Each data file has a filename that contains the word "metrics".

To do this, I am using the following to read these into a struct:

>> F = dir("*metrics*")

This works. I get the following:

F = 
  3×1 struct array with fields:
    name
    folder
    date
    bytes
    isdir
    datenum

I happen to know that in this test directory, there are 3 files that match this pattern, and in the above return I can see that F is a 3x1 struct array.

Accessing F(1).name gives the name of the first file, F(2).name gives the name of the second and so on.

The problem I have is that in the live directory (not the test one) there can be an unknown number of files, and I need to process each one of them in turn.

I though that I could use 'size' to get the dimensions of the struct array (as returned in the above), but I get this instead:

>> size F  
  
ans =
     1     1

So, the quesiton is, how do I figure out how many filename "entries" there are in this struct F, so that I can use a loop to process each index in turn?

I was planning on doing something like this:

     for index = 1:numberOfFiles
        myFileProcess(F(index))
     end

Please note that I am not asking about how to access individual elements of the entries in the struct (like b = F(2).bytes) - I need to know how many things there are in this struct (i.e filenames returned from dir).

Thanks!