How to find the maximum index in a struct

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!

[Stephen23]

Note that

size F

is equivalent to

size('F')

which measures the size of the scalar character 'F' (note that strings are colored purple). Compare:

size(F) % what you should do

https://www.mathworks.com/help/matlab/matlab_prog/command-vs-function-syntax.html

Answer 1

[Star Strider]

Try something like this instead:

Fsize = size(F)

The function form is likely to give the result you want.

EDIT — (23 Apr 2021 at 4:30)

If you only want to know how many files there are in ‘F’:

Flen = numel(F)

works.

[EK]

Thanks!

Flen = numel(F)

is exactly what I was looking for.

Appreciate the help.

[Star Strider]

As always, my pleasure!