How to use multiple variables in a name structure

Hello,

a simple question please answer or show me a help file - I can't find it:

I get a filename

fig_name = [name, '_PLL.png'];

and get

'001_m1_60_const_20200611_200515_PLL.png'

now, I want have more variable in my fig_name, to get:

'001_m1_60_const_20200611_200515_SNR_1_PLL.png'
'001_m1_60_const_20200611_200515_SNR_2_PLL.png'
'001_m1_60_const_20200611_200515_SNR_3_PLL.png'
...
'001_m1_60_const_20200611_200515_SNR_N_PLL.png'

I tried allready with:

fig_name = [name,'_SNR_',SNR,'_PLL.png']

but I get just:

fig_name =  '001_m1_60_const_20200611_200515_SNR__PLL.png'

What is wrong? What is a rule to create a names with usin of variables?

Thank you!

Answer 1

[madhan ravi]

 compose('001_m1_60_const_20200611_200515_SNR_%d_PLL.png', (1:3).')

[Nik Rocky]

Thank you, but i want also change a name variable:

'001_m1_60_const_20200611_200515_SNR_1_PLL.png'
'001_m1_60_const_20200611_200515_SNR_2_PLL.png'
'001_m1_60_const_20200611_200515_SNR_3_PLL.png'
...
'001_m1_60_const_20200611_200515_SNR_N_PLL.png'
'002_foofoo_SNR_1_PLL.png'
'002_foofoo_SNR_2_PLL.png'
'002_foofoo_SNR_3_PLL.png'
.......
'002_foofoo_SNR_N_PLL.png'
'003_testtest_SNR_1_PLL.png'
............

so it should be 2 variables in fig_name: name and SNR. (two loops) It is possible?

[Nik Rocky]

I get it:

fig_name = [name,'_SNR_',num2str(SNR),'_PLL.png']

fig_name =

    '001_m1_60_const_20200611_200515_SNR_2_PLL.png'
    

and for loop:

for i = 1:SNR
    fig_name = [name,'_SNR_',num2str(i),'_PLL.png']
    ..........
end

[Image Analyst]

Or for those of us who prefer sprintf():

for k = 1 : SNR
    fig_name = sprintf('%s_SNR_%d_PLL.png', name, k)
end

[madhan ravi]

Thank you sir Image Analyst.

[Nik Rocky]

Yes, thank you!

Answer 2

[Stephen23]

The most efficient approach is to use sprintf (and is what experienced MATLAB users would do):

for k = ...
    fig_name = sprintf('%s_SNR_%u_PLL.png',name,k);
    ...
end

You should avoid using i as a variable name, as this shadows the inbuilt imaginary unit i.

[madhan ravi]

Note using i as a variable is not recommended.

[Nik Rocky]

Yes, thank you very much!

%s = string ?

%u = uint/value ?

[Stephen23]

"Note using i as a variable is not recommended."

I guess that should be a comment to the OP here. As Madhan ravi notes, i is best avoided.

https://www.mathworks.com/matlabcentral/answers/175449-i-and-j-as-variable-names-vs-imaginary-unit-what-advice-to-give-on-matlab-answers

[Stephen23]

%s = string ?
%u = uint/value ?

Correct. Read more about the format options here:

https://www.mathworks.com/help/matlab/ref/sprintf.html

[Nik Rocky]

I found it

[Stephen23]

What you showed is a table for C's sprintf, apparently copied from here:

http://www.cplusplus.com/reference/cstdio/printf/

It supports a different set options than MATLAB's sprintf, although there is some overlap.

To know what options MATLAB's sprintf supports, refer to the MATLAB documentation:

https://www.mathworks.com/help/matlab/ref/sprintf.html

[Nik Rocky]

Oh, thank you! Its good to know. than the table is not compatible. Should I better delete it?