Speed up string Assembly

Hi all,

Question: I try to assamble strings with the following loop (ch_empty10 = ' ', and db_Value(i) = e.g. 4.1563):

for i = 1:100000
   ch_String = [ch_String, ch_empty10(1:10-length(num2str(db_Value(i)))),num2str(db_Value(i))]   %(-> would result in '    4.1563')
end

In my application I have >100'000 different db_Values and all need to be assembled the same way and are combined to one string. Is there somehow a way that I can avoid using a loop that goes thru all nodes to speed up the process.

I hope I formulated the question clear enough. Thanks for your help! Best, J

Answer 1

[Jonas Widmer]

Ah, think I found the solution:

ch_String = sprintf('%10.4f%10.4f%10.4f\r\n', [my_Matrix]')

Answer 2

[Walter Roberson]

ch_String = sprintf('%10.4f', db_Value);

No loop. This does everything at the same time.

Answer 3

[Jonas Widmer]

Cool! Thanks a lot for the quick answer. That's an awesome solution. Didn't know the sprinf command. My actual application is however a little more complex than I explained above:

I have a matrix 3 x >100'000 and in the end I try to have this in a .txt file. Is there a way to assemble the matrix that I have this shape in the end:

 '     5.2342    1.2315    156.1561\r\n     453.1236     12.1231     15.1231\r\n    1.1561    8.8912      5.5613\r\n'

When my matrix is:

       my_Matrix = [5.2342, 1.2315, 156.1561;...
                    453.1236, 12.1231, 15.1231;...
                    1.1561, 8.8912, 5.5613]

Cheers, J