How can I output only part of a array?

I wrote a code that plots a function for me. In the code, an array is given the name of the selected file. Example: FileName = 'Evaluation_114_1688.xlsm'

I would now like to save the figure as a jpg, which is why I used the command: saveas(gcf,FileName,'jpg')

But I would like to use only the numbers from the file name: 114_1688.jpg

How is it possible for me to select only the numbers from the file name?

Answer 1

[KSSV]

FileName = ['114_1688','.jpg'] ; 
saveas(gcf,FileName) 

[Andy]

But everytime I run the code, I chose a other file. That means that the FileName is constantly changing. I need a command that recognizes the numbers in the array and names the jpg only after the numbers.

[KSSV]

[filepath,name,ext] = fileparts('Evaluation_114_1688.xlsm') ; 
FileName = strcat(name,'.jpg') ;
saveas(gcf,FileName) 

Answer 2

[Voss]

This may work for you:

FileName = 'Evaluation_114_1688.xlsm';

new_name = regexp(FileName, '_([\d_]+\.)', 'tokens', 'once');
%                            ^              leading underscore
%                              ^^^^^^       followed by one or more (+) digit (\d == 0-9) or underscore (_) characters
%                                    ^^     followed by a period
%                             ^        ^    group everything after the leading underscore, up to and including the period, in a "token" to be returned

new_name = [new_name{1} 'jpg']

new_name = '114_1688.jpg'