sprintf: how to efficiently create a string of 75 numbers, separated by comma

I have an array which contains 75 numeric elements. I want to write these numbers as a string separated by a comma. If there were few numbers, I could use 'sprintf' as follows:

 A=[1,2];
 str=sprintf('%d,%d',A(1:end));

I need an efficient way to do it when there are many entries in A.

Answer 1

[Star Strider]

You can still use sprintf. You just need to create a ‘dynamic’ format string:

A = 1:5;
str = sprintf([repmat('%d,',1, numel(A)-1), '%d'], A)

str =
    '1,2,3,4,5'

That will adapt for any ‘A’ vector.

[Abhinav]

Thanks a lot!

[Star Strider]

As always, my pleasure!

Answer 2

[Ameer Hamza]

This will work.

strjoin(string(A), ',')

[Walter Roberson]

Note: this requires R2016b or later. Also, it creates a string object output, not a character vector.

[Ameer Hamza]

Thanks for elaborating.

Answer 3

[Stephen23]

"I need an efficient way to do it when there are many entries in A."

This is probably about the most efficient way:

A = 1:5;
str = sprintf(',%d',A);
str = str(2:end);

Timing comparisons for 1e4 iterations:

Elapsed time is 0.539053 seconds. % this answer.
Elapsed time is 2.54425 seconds.  % Star Strider's answer.

[Walter Roberson]

I didn't answer -- I commented on someone else's answer.

[Stephen23]

@Walter Roberson: you are right, sorry for the confusion. I fixed the reference.