Appending string to Matlab array

Question

How do I append a string to a Matlab array column wise?

Here is a small code snippet of what I am trying to do:

for_loop
  filename = 'string';
  name=[name; filename]
end

Solution 1

You need to use cell arrays. If the number of iterations are known beforehand, I suggest you preallocate:

N = 10;
names = cell(1,N);
for i=1:N
    names{i} = 'string';
end

otherwise you can do something like:

names = {};
for i=1:10
    names{end+1} = 'string';
end

Solution 2

As other answers have noted, using cell arrays is probably the most straightforward approach, which will result in your variable name being a cell array where each cell element contains a string.

However, there is another option using the function STRVCAT, which will vertically concatenate strings. Instead of creating a cell array, this will create a 2-D character matrix with each row containing one string. STRVCAT automatically pads the ends of the strings with spaces if necessary to correctly fill the rows of the matrix:

>> string1 = 'hi';
>> string2 = 'there';
>> S = strvcat(string1,string2)

S =

hi
there

Solution 3

As noted elsewhere, in MATLAB all strings in an array must be the same length. To have strings of different lengths, use a cell array:

name = {};
for i = somearray
  name = [name; {string}];
end

Solution 4

Use strcat function to append using one line code without using loop:

A={'food','banana','orange'}

A = 'food' 'banana' 'orange'

A = strcat(A,'s')

A = 'foods' 'bananas' 'oranges'

Solution 5

name=[];
for_loop
    filename = 'string';
    name=[name; {filename}];
end

View more solutions

Comments

[Andrew Janke]

Using the { ... } to construct iteratively like this will end up with a nested cell array like a tree or a Lisp list, not a cellstr. How about "strs = {'a string'}; for i=1:3; strs = [strs; {new_string(i)}]; end" or "... strs{end+1} = new_string(i); ..."?

[Joseph Lisee]

Wow, thanks for the {end+1} syntax, I didn't even know "end" existed in that context.

[Yauhen Yakimovich]

Yes {end+1} is much better than {length(..)+1}!

[Sibbs Gambling]

plus 1; thanks! Didn't know strcat works for uneven-sized concatenation!

[Danijel]

I need to use the names as input to fopen, however, fopen is complaining that it's a wrong type: cell. How would I convert cell type to string?