how to prealloacte and store values in a character array?
59 views (last 30 days)
Show older comments
Hi! :)
I want to make a character array consisting of 3 rows and 2 strings and firstly I dont know how I can preallocate it. I also tried to store values in it ( in the first row) using the attached code but failed to do so
best_salt_1 = "ZnBr2";
best_salt_2 = "Format";
combinations_of_best_salts=char(zeros(antall_soner,2))
combinations_of_best_salts(1,1:strlength(best_salt_1))=best_salt_1;
combinations_of_best_salts(1,strlength(best_salt_1):18- strlength(best_salt_2))=best_salt_2;
disp(combinations_of_best_salts)
4 Comments
Stephen23
on 2 Aug 2022
Edited: Stephen23
on 2 Aug 2022
@Muazma Ali: please show the expected output (not a description).
Answers (1)
Stephen23
on 12 Aug 2022
Edited: Stephen23
on 12 Aug 2022
I am guessing that your strings have different lengths on different loop iterations, in which case it mght not be obvious how to preallocate the array.
Here are two alternative approaches:
N = 7; % number of rows
Character array (preallocated rows, expand columns as required):
M = char(nan(N,0));
for k = 1:N
[S1,S2] = rndstr(k); % random strings
V = sprintf('%s %s',S1,S2);
M(k,1:numel(V)) = V;
end
display(M)
Cell array to collect data, CHAR() after the loop:
C = cell(1,N);
for k = 1:N
[S1,S2] = rndstr(k); % random strings
C{k} = sprintf('%s %s',S1,S2);
end
M = char(C{:})
function [st1,st2] = rndstr(k)
rng(k);
st1 = string(char(randi([33,126],1,randi([3,7]))));
st2 = string(char(randi([33,126],1,randi([3,7]))));
end
4 Comments
Stephen23
on 12 Aug 2022
Edited: Stephen23
on 12 Aug 2022
"what is the input k in your last alternative..?"
k is the loop iterator. You can find the MATLAB documentation for FOR loops here: https://www.mathworks.com/help/matlab/ref/for.html
It is not clear what you mean by "input k": I provided the iterator as an input to my fake-data generator function in order to reset the random number generator, so that both loops would provide exactly the same random numbers and give exactly the same output character matrix. This is completely superfluous and unrelated to the answer, because of course you would use your strings, not my fake data.
"can you try to explain what your last alternative does, line by line.., please?"
C = cell(1,N); % preallocate a cell array to hold character vectors
for k = 1:N % loop N times
[S1,S2] = rndstr(k); % create fake data strings (you use your strings)
C{k} = sprintf('%s %s',S1,S2); % create character vector and store in cell array
end %
M = char(C{:}) % join all character vectors into one character matrix
Note that CHAR() automatically pads the character vectors with spaces, in order to create the matrix.
See Also
Categories
Find more on Multidimensional Arrays in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!