Hi, hope you are well

In the first image is code that takes multiple hdf files of images and creates a subplot/grid which works perfectly fine (see the second image).

My question to you is simple: The hdf files are numbered from 56-67

At the moment these are plotted in a random order (see the second image for reference).

What do I implement into the code I have shown in the first image to order/sort these hdf files in the correct order?

I have tried: hdf_files = sorted(hdf_files, key=lambda x: int(x.split('_')[1])). This is inserted before the for loop in the first image of code however I get the error 'local variable 'hdf_files' referenced before assignment'

It should go 56, 57,58, 59 and so on...

Kindly rewrite my script (first image) that works with the extra bit of code that sorts the files into order :)

Thanks in advance.

\begin{tabular}{|c|c|c|c|} \hline 62 & 57 & 60 & 64 \\ \hline 58 & 65 & 56 & 61 \\ \hline 63 & 59 & 66 & 67 \\ \hline \end{tabular}